17) David was asked to solve the problem below:
If a = 5x - 4 and b = 3x, what is the value of a - b?
David used the steps below to solve the problem
Step 1: a - b
Step 2: (5x-4) - 3x
Step 3: 5x-4-3x
Step 4: -2x
Determine whether David's solution is correct. If he is correct, show the work that proves he is
correct. If he made an error, explain what he should have done instead, and provide the correct
solution.