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)
