Which expression represents the average of three test scores? x + y + z 3 (x + y + z) StartFraction x + y + z over 3 EndFraction StartFraction x y z over 3 EndFraction

To solve the system of equations below, pedro isolated the variable y in the first equation and then substituted it into the second equation. what was the resulting equation? { 5y=10x {x^2+y^2=36