Have questions I don’t know how to answer

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

Which graph represents the equation y =4x

Aright cylinder has a diameter of 8 m and a height of 6m. what is the volume of the cylinder