Answer:
97
Explanation:
Relative to the average she wants, Carolyn's scores are ...
85-85 = 0
77-85 = -8
81-85 = -4
Carolyn's score total is -8-4 = -12 points from the average she wants, so she must get 85+12 = 97 on her speech to achieve a B+ average.
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Check
With a 97, Carolyn's average would be ...
(85 +77 +81 +97)/4 = 340/4 = 85