Missing angles in triangle help

Which expression is equivalent to7_/x^2 ÷ 5_/y^3? assume y# 0

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?

The figures below are made out of circles, semicircles, quarter circles, and a square. find the area and the perimeter of each figure and give your answers as a completely simplified exact value in terms of π (no approximations).