Becky and Tommy are asked to solve −4x − 25 = 8x + 15. Identify where one of them made an error. BECKY:
−4x − 25 = 8x + 15
−4x − 25 − 8x = 8x + 15 − 8x
−12x − 25 = 15
−12x − 25 + 25 = 15 + 25
−12x = 40
Negative 12x over 40 equals 40 over 40
x equals negative three-tenths
TOMMY:
−4x − 25 = 8x + 15
−4x − 25 + 4x = 8x + 15 + 4x
−25 = 12x + 15
−25 − 15 = 12x + 15 − 15
−40 = 12x
negative 40 over 12 equals 12x over 12
x equals negative ten-thirds
(1 point)
Becky made the error when she subtracted 8x
Becky made the error when she divided by 40
Tommy made the error when he added 4x
Tommy made the error when he added 15