Solving equations using subtraction

When solving equations using subtraction, these equations will have the form x + b = c. Recall that ax + b = c is a linear equation.

Therefore, the equation x + b = c is also a linear equation with a = 1.

In order to this see this, notice that 1x = x. Thus, we can rewrite x + b = c as 1x + b = c and it will have the same format as ax + b = c.

You can solve x + b = c in one step.

When solving one step equation of the form x + b = c, subtract b from both sides of the equation.

x + b = c

x + b - b = c - b

x + 0 = c - b

x = c - b

A few of examples showing how to solve equations using subtraction.


We will illustrate with 3 examples.

Example #1: Solve the equation x + 3 = 8 for x using subtraction.

Solving  x + 3 = 8

Alternatively, you do not need to put the -3 beneath the 3. You can also put the -3 next to it.

x + 3 = 8

x + 3 - 3 = 8 - 3

x + 0 = 5

x = 5

Example #2: Solve the equation x + 5 = 10 for x using subtraction.

Solving  x + 5 = 10

Alternatively, you do not need to put the -5 beneath the 5. You can also put the -5 next to it.

x + 5 = 10

x + 5 - 5 = 10 - 5

x + 0 = 5

x = 5

Example #3: Solve the equation x + 5 = -10 for x using subtraction.

Solving x + 5 = -10

Alternatively, you do not need to put the -5 beneath the 5. You can also put the -5 next to it.

x + 5 = -10

x + 5 - 5 = -10 - 5

x + 0 = -15

x = -15

A quick way to solve equations of the form x + b = c

As already demonstrated above, if x + b = c, then x = c - b. Here are some examples.

If x + 6 = 2, then x = 2 - 6 = -4

If x + -4 = 4, then x = 4 - -4 = 4 + 4 = 8

If x + 2 = 9, then x = 9 - 2 = 7

If x + -2 = -9, then x = -9 - -2 = -9 + 2 = -7

Solving equations using subtraction. Can you get 100% on this quiz?





Recent Articles

  1. 45-45-90 Triangle

    May 01, 23 07:00 AM

    45-45-90 triangle
    What is a 45-45-90 triangle? Definition, proof, area, and easy to follow real-world examples.

    Read More

  2. Theoretical Probability - Definition, Explanation, and Examples

    Apr 24, 23 07:02 AM

    Theoretical probability versus experimental probability
    Learn how to compute the likelihood or probability of an event using the theoretical probability formula.

    Read More

Tough algebra word problems

100 Tough Algebra Word Problems.

If you can solve these problems with no help, you must be a genius!

Math quizzes

 Recommended

Math vocabulary quizzes