Answer: Part A: Margie made an error in the first step of her work. The error lies in her attempt to simplify the expression (−3.12b + 12) − (4.36b − 11). She added the positive constant term 12 to the negative coefficient −4.36b, which resulted in −4.36b + 12. However, she should have subtracted 12 from −4.36b, which would have given her −4.36b − 12 instead. Part B: To correctly write the expression in the fewest terms, we need to correct the error in Part A. We start with the original expression (−3.12b + 12) − (4.36b − 11). To simplify it, we distribute the negative sign to each term inside the second set of parentheses, which gives us (−3.12b + 12) + (−4.36b + 11). Now, we can combine like terms. First, we add the −3.12b and −4.36b terms, which gives us −7.48b. Then, we add the 12 and 11 terms, which gives us 23. Therefore, the correct simplified expression is −7.48b +