In which choice is y not a linear function 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

Rose bought a new hat when she was on vacation. the following formula describes the percent sales tax rose paid b=t-c/c

Math question.. plz me .. best answer all