Breann solved the system of equations below. What mistake did she make in her work?

2x + y = 5
x − 2y = 10

y = 5 − 2x
x − 2(5 − 2x) = 10
x − 10 + 4x = 10
5x − 10 = 10
5x = 20
x = 4

2(4) + y = 5
y = −3

She should have substituted 5 + 2x

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

She subtracted 10 from both sides instead of adding 10 to both sides

She made no mistake

Question

Breann solved the system of equations below. What mistake did she make in her work?

2x + y = 5
x − 2y = 10

y = 5 − 2x
x − 2(5 − 2x) = 10
x − 10 + 4x = 10
5x − 10 = 10
5x = 20
x = 4

2(4) + y = 5
y = −3

She should have substituted 5 + 2x

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

She subtracted 10 from both sides instead of adding 10 to both sides

She made no mistake

turingtest · Answer

I see no mistakes

anonymous · Answer

agreed

anonymous · Answer

Sorry, that is no answer.

The real answer here is that you should plug the values of x and y in the original equations and see if the two equations satisfy. If they do, then there is no mistake. That is the ONLY way to confirm there is no mistake.

anonymous · Answer

So, plug in x = 4 and y = -3 in the original two equations.