Ok, so to clarify, she went to 3 stores, is that right? I’ll do this as if the answer is yes. I’ll fix it in comments if your answer is no.
(14.28b + 24) + (27)
14.28b + 51 = amount spent after 2 stores
Then the third store:
14.28b + 78
If b = 2,
14.28(2) + 78 = 28.56 + 78 = $106.56