Question

Kisha and Rae are asked to solve −5x − 14 = 2x + 7. Identify where one of them made an error.


Kisha
Rae
−5x − 14 = 2x + 7
−5x − 14 − 2x = 2x + 7 − 2x
−7x − 14 = 7
−7x − 14 + 14 = 7 + 14
−7x = 21
Negative 7x over negative 7 equals 21 over negative 7
x = − 3
−5x − 14 = 2x + 7
−5x − 14 + 5x = 2x + 7 + 5x
−14 = 7x + 7
−14 + 7 = 7x + 7 + 7
−7 = 7x
negative 7 over 7 equals 7x over 7
x = − 1
Rae made the error when she added 7

Rae made the error when she added 5x

Kisha made the error when she subtracted 2x

Kisha made the error when she divided by −7