Question

Which operation is used to solve for x?

Answer 1

subtraction

Explanation:

if you take -21 and subtract 8 you get -29

if you then add 8 to -29 you get -21 to check your answer

Answer 2

Subtraction

Explanation:

Since 8 is being added to the x, in order to get rid of it on the left side to solve for x you need to subtract 8 on both sides.