Question

Luka, Zara, and Kim simplified the following expression: -3(x+4) – 2(5x – 6). Their work
is shown below. Who simplified the expression correctly? Explain your answer. (Hint:
None, one, or two of the students could be correct.)
I
Luka
-3(x+4) - 2(5x-6)
-3(x+4) + -2(5x + -6)
-3x + -12 + -10x + 12
-13x
Zara
-3(x+4) - 2(5x-6)
-3x + -12 - (10x -12)
-3x + -12 - 10x + 12
-13x
Kim
-3(x+4) - 2(5x - 6)
-3x + -12 - 10x - 12
-13x - 24

Answer 1

Answer:

Kim and Zara are correct.

Step-by-step explanation:

Correct simplification:

-3(x+4) - 2(5x-6)

-3x + (-12) - 10x + 12

-3x - 12 - 10x + 12

- 13x

• Luka is correct.
• Zara is correct.

• Kim is incorrect because when -2 is distributed to (5x-6), it should come out to be -10x+12.