Answer: The answer is in the explanation.
Step-by-step explanation:
Part A: Margie made an error in step 2 when they didn't make 5.38b a negative number. It should be a negative number because when you use the additive inverse, you multiply the number by -1, and you get -5.38b.
Part B: The correct way to write the expression in the fewest terms is by first removing the parenthesis from the expression. Then, you arrange the like terms. You would move -5.38b to its like term, so you would put in parenthesis since you are arranging it. Next, you will put parenthesis around the like terms. Also, since there isn't a minus sign, you won't need to add the additive inverse. Then you just add -2.67b + 5.38b = 2.71b. And then 11 + 15 = 26.
I hope I explained it clearly!