Please please help me with this work.

If f(x)= 3x+6 which of the following is the inverse of f(x)

Problem melissa is her dad build a walkway in their backyard. the walkway will be 54 feet long and 1.5 feet wide. the local hardware store sells tiles which are 1.5 by 1.5 feet and come in boxes of 12. how many boxes of tiles do they need?

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).