Plz help the question is in the photo plz

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

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

The difference between two numbers is one. three times the larger number minus two times the smaller number is 9. what are the two numbers