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.

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?





Related content

Linear equations calculator
Easily solve equations of the form x + b = c with the click of a button!

Recent Articles

  1. Discrete and Continuous Data

    Sep 17, 20 03:57 PM

    Learn clearly the difference between discrete and continuous data with good examples.

    Read More

New math lessons

Your email is safe with us. We will only use it to inform you about new math lessons.

                                 Follow me on Pinterest

Real Life Math Skills

Learn about investing money, budgeting your money, paying taxes, mortgage loans, and even the math involved in playing baseball.