Question

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

Answer 1

2x + y = 5

x − 2y = 10

y = 5 − 2x

x − 2(5 − 2x) = 10

x − 10 + 4x = 10

5x − 10 = 10

add 10 to each side

5x-10+10 = 10 + 10

5x=20

5x = 0    this is the error

He needs to add 10 to each side