Trevor solved the system of equations below. What mistake did he make in his work?


2x + y = 5

x - 2y = 10


y = 5 - 2x

x - 2(5 - 2x) = 10

x - 10 + 4x = 10

5x - 10 = 10

5x = 0

x = 0


2(0) + y = 5

y = 5

Answer


He made no mistake


He subtracted 10 from the right side instead of adding 10 to the right side


He combined like terms incorrectly, it should have been 4x instead of 5x


He should have substituted 5 + 2x