Margie's work for adding linear expressions is shown below. After checking her answer with the answer key, she solved it incorrectly.


Given (−1.56b + 10) − (4.27b − 14)
Step 1 −1.56b + 10 + (−4.27b) + 14
Step 2 −1.56b + 4.27b + 10 + 14
Step 3 (−1.56b + 4.27b) + (10 + 14)
Step 4 2.71b + 24


Part A: Identify and explain the first step where Margie made an error. (6 points)

Part B: Explain how to correctly write the expression in fewest terms by correcting the error in Part A. Show all work. (6 points)