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
