Question

what inverse operation would I use to solve x+12=48?

Answer 1

subtract the 12 from the 12, and then from the 48. You will mow have this:
$x = 36$
Subtraction, if its a word answer.

Answer 2

Hi!

The inverse operation used is subtraction
 
Using subtraction you would get x=36 by subtracting both sides of the equation by 12 leaving you with x=36.