The procedure to solve an equation by adding a number to both sides of the equation is outlined below

Example: x - 5 = -7

You entered the following equation x - 5 = -7

Change the minus into plus and the take the opposite of 5

x + -5 = -7

Add 5 to both sides of the equations

x + -5 + 5 = -7 + 5

Do the math for -5 + 5 and -7 + 5

-5 + 5 = 0

-7 + 5 = -2

Rewrite the equation

x + 0 = -2

we get:

x = -2