Step 1: Find f(x)^-1(Inverse function of x)
Step 2: Find f(-7)^-1(Plug -7 into your inverse function)
Step 3: (foff^-1)(-7) Means f(-7) composite f(-7)^-1, which means plug the inverse function of -7(we found that back in step 2) in for x in the f(x) function and solve.
Hope this helps!