The answer depends upon what you are trying to find the value of like value of y or value of z. The person above did give you the correct way to solve for the value of y which is 4.5 as the answer.
However, if you need to solve for the value of z, then use ratio of side BC/side FG = side CD/side GH, which is:
8/6=10/z (cross multiply) to get 8z=6*10 then divide both sides by 8 to solve for z. 8z/8=60/8 then z=7.5 .