Need to find the value of x

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 function , when d = {9, 15, 30}. r = {5, 7, 12} r = {6, 10, 15} r = {6, 10, 20} r = {5, 12, 20}

If you were constructing a triangular frame, and you had wood in the length of 4inches, 4 inches, and 7 inches, would it make a triangle? would you be able to create a frame from these pieces of wood? yes or no. explain your mathematical thinking