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Last updated on October 16, 2025

Applications of Linear Equations

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Linear equations are used in mathematics as well as in real life. An equation with a degree of one is known as a linear equation. The statement that shows two expressions are equal and includes variables and an equal sign is known as an algebraic equation. In this article, we will learn about applications of linear equations.

Applications of Linear Equations for US Students
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What are Linear Equations?

A linear equation is an equation where the highest power of the variable is 1. It can involve one variable, two variables, and more. A linear equation combines variables and constants, where the variables have a power of 1. Ax + By = C is the standard form of a linear equation, where a and b are coefficients, x and y are variables, and c is the constant. Linear equations form a straight line if plotted on a graph. The graph of a linear equation is given below:

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What are the Applications of Linear Equations?

The applications of linear equations are vast. While solving real-life problems using algebra, we change the given situation into a mathematical statement that clearly explains the relationship between the unknown variables and the information provided. Here are the steps to turn a real-life problem into a mathematical statement. 

  • Change the problem statement to a mathematical statement and set it up in the form of an algebraic expression that describes the problem exactly.
  • Find the unknown values in the problem and represent them using variables. 
  • Read the problems multiple times and mark the data, keywords, and phrases. Organize the information sequentially. 
  • Form an equation using the given information and algebraic expressions, then solve it using suitable methods.
  • Recheck the solution to your problem statement and analyze whether it suits the criteria of the problem. 

Using these steps and the applications of linear equations, word problems can be solved easily. Linear applications are used in real life to find unknown ages, calculate speed, distance, or time, and solve problems related to force and pressure. 
 

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Real-Life Applications of Linear Equations

Linear equations are used not only in academics but also in many fields such as finance, engineering, science, and everyday life. By representing real-life situations in mathematical terms, linear equations help to predict outcomes, calculate unknown values, make predictions, and analyze relationships. Below are some of the real-life applications of linear equations. 

  • Finance and Budgeting: In finance and budgeting, linear equations are used to calculate expenses, savings, and profits. If a company knows its fixed cost and variable cost per unit, it can find the break-even point by solving a linear equation. 
  • Construction and Architecture: Engineers and architects use linear equations to calculate dimensions, costs, and material requirements. For example, if the cost of materials increases in proportion to the area, we can use a linear equation to calculate the total cost. 
  • Agriculture and Farming: Farmers use linear equations to predict crop yields based on the fertilizers used, land area, or costs. If every acre of land produces 2 tons of wheat, the total yield Y is Y = 2x, where x is the total acres. 
  • Chemistry: In chemistry, linear equations help in mixing solutions of different concentrations to achieve a desired mixture. A chemist can use a linear equation to calculate how much of each solution is needed to get a mixture with a desired concentration. 
  • Everyday Problem-Solving: Linear equations are used in everyday problem-solving in situations such as dividing expenses among friends, or calculating taxi fares, which involve linear equations.  
     
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Common Mistakes and How to Avoid Them in Linear Equations

Mistakes are common when dealing with the applications of linear equations. Given below are some of the common mistakes and the ways to avoid them.

Mistake 1

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Mixing variables and constants
 

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Students sometimes forget which are constants and which are variables. For example, 50 + 10x = 150, students may think that 50 and 10 are variables. Always remember that variables are represented by letters like x, y, or z, while constants are just numbers.

Mistake 2

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Doing wrong operations on both sides
 

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While solving linear equations, some students add a number on one side but forget to do the same on the other side. Think of the equation as a weighing scale; whatever you do on one side must be done on the other side to keep it balanced. If we subtract 5 on the left, we must also subtract 5 on the right.

Mistake 3

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Confusing the order of operations
 

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Students solve equations from left to right instead of following the BODMAS rule. Remember that BODMAS stands for Brackets, Orders, Division/Multiplication, Addition, and Subtraction. 
 

Mistake 4

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Forgetting the units
 

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Forgetting the units like km, kg, or $ in the final answer, even when the calculation is correct, will lead to a mistake. After solving the problem, double-check the question to ensure you include the correct unit.
 

Mistake 5

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Guessing instead of solving
 

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Without forming the correct equation, students sometimes try random numbers until they get the answer. Form a proper linear equation first. It saves time and avoids errors. 
 

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Solved Examples of Linear Equations

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Problem 1

A taxi charges $50 as a base fare and $10 per kilometer. If you paid $150 for a ride, how many kilometers did you travel?

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You traveled 10 kilometers.
 

Explanation

The total fare can be written as: F = 50 + 10x, here x is the kilometers
We know that the total fare is $150.
150 = 50 +  10x
150 - 50 = 10x
100 = 10x
x = 100/10
x = 10
So, the distance traveled is 10km.
 

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Problem 2

Ravi has $200. He spends $20 every day. After how many days will he have $60 left?

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 It will take 7 days.
 

Explanation

 Let x be the number of days
The money left can be written as: 200 - 20x = 60
Subtract 200 from both sides: -20x = 60 - 200
-20x = -140
Divide by -20: x = 7
So, after 7 days, he will have $60 left.
 

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Problem 3

A father is 30 years older than his son. In 10 years, the father will be twice as old as his son. What is the son's current age?

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 The son is 20 years old.
 

Explanation

Let the son’s age be x. Then, the father’s age is x + 30
After 10 years, Son’s age = x + 10
Father’s age = x + 30 + 10 = x + 40
According to the problem, x + 40 = 2x + 20
x + 40 = 2x + 20
Subtract x:
40 = x + 20
x = 40 - 20
x = 20
 

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Problem 4

A bag of apples costs $50, and each orange costs $5. If a person spends $100 on buying 1 bag of apples and some oranges, how many oranges did they buy?

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They bought 10 oranges.
 

Explanation

 Let the number of oranges be x
Total cost = cost of apples + cost of oranges
50 + 5x = 100
Subtract 50 from both sides: 5x = 50 
Divide by 5: x = 10
Hence, they bought 10 oranges.
 

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Problem 5

A machine prints 40 pages in 1 minute. How many minutes will it take to print 200 pages if it starts with 20 pages already printed?

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 It will take 5 minutes
 

Explanation

Pages to print = 200 - 20 = 180 pages
Let x be the number of minutes needed
Pages printed in x minutes = 40x
So, 40x = 180
Divide both sides by 40: x = 180/ 40 = 4.5 minutes.
Therefore, the machine will take approximately 5 minutes.

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FAQs on Linear Equations

1.What is a linear equation?

A linear equation is an equation where the highest power of the variable is 1, and it represents a straight line when drawn on a graph. 
 

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2.Why are linear equations important?

Linear equations are important because they help us solve problems quickly by using a simple formula. 
 

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3.What is the easiest way to form a linear equation from a problem?

To form a linear equation, read the problem carefully, find the constants and variables, and write an equation using them. 
 

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4.Can linear equations have more than one solution?

Yes, if a linear equation has two variables, it has infinitely many solutions, which lie on a straight line. 
 

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5.Where do we see linear equations in real life?

We see linear equations in things like calculating taxi fares, planning budgets, finding distances, predicting profits or losses in business, and even in everyday shopping.
 

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Jaskaran Singh Saluja

About the Author

Jaskaran Singh Saluja is a math wizard with nearly three years of experience as a math teacher. His expertise is in algebra, so he can make algebra classes interesting by turning tricky equations into simple puzzles.

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Fun Fact

: He loves to play the quiz with kids through algebra to make kids love it.

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