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

A) He should have substituted 5 + 2x
B) He combined like terms incorrectly, it should have been 4x instead of 5x
C) He subtracted 10 from the right side instead of adding 10 to the right side
D) He made no mistake

Question

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

A) He should have substituted 5 + 2x
B) He combined like terms incorrectly, it should have been 4x instead of 5x
C) He subtracted 10 from the right side instead of adding 10 to the right side
D) He made no mistake

bigbosssaint21 · Answer

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

heathero · Answer

The other person is right but please refrained from posting math questions on history subjects.