How are addition and multiplication used to solve a linear equation? Demonstrate by solving "15x + 7 = 31 + 3x?

15x + 7 = 31 + 3x
15x - 3x = 31 - 7
12x = 24
x = 2

gather like terms:  subtract 3x from both sides and subtract 7 from both sides.

15x-3x = 31-7

combine like terms

12x = 24

divide both sides by 12

12x/12 = 24/12

x =2

15x + 7 = 31 + 3x
15x - 3x = 31 - 7
12x = 24
12x / 12 = 24 / 12
x = 2

Checking : Substitute the value of " x ".
15x + 7 = 31 + 3x
15 ( 2 ) + 7 = 31 + 3 ( 2 )
30 + 7 = 31 + ( 6 )
37 = 37


15x + 7 = 31 + 3x
Join the like terms, when moved to the other side its sign changes.
15x - 3x = 31 - 7
Add and/or subtract each side.
12x = 24
Find a number that is divisible by both sides and that will retain " x "
12x / 12 = 24 / 12
Divide them to that number and you will get the value of " x " or the unknown number.
x = 2

In checking, just substitute the value of " x ".

My Answer :
x = 2

15x + 7 = 31 + 3x
12x = 24
x = 2.
multiplication is not used to solve this equation.