(Properties of Operations HC)
On a recent exam, a student was asked
to simplify the expression:
12(8x - 4y) - 3(12y + 9x)
Their work IS shown below:
Step 1: 12(8x - 4y) - 3(12y + 9x)
Step 2: 96x - 48y - 36y + 27x
Step 3: 96x + 27x - 48y - 36y
Step 4: (96X + 27x) + (-48y - 36y)
Step 5: 123x - 84y
Part A: In which step did they make a mistake, and what was it? (2 points)
Part B: How would you correct the mistake and solve the problem? Show all of your work. (2 points)