Simplify rational expression with positive exponents

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

To solve the system of equations below, grace isolated the variable y in the first equation and then substituted into the second equation. what was the resulting equation? 3y=12x x^2/4+y^2/9=1

Evaluate the expression for the given value of the variable. ∣-4b-8∣+∣-1-b^2 ∣+2b^3 ; b=-2