SOLUTION: What must Sara get on here next test to average 80% if her previous test scores were 78, 88, 83, and 81?

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Question 633848: What must Sara get on here next test to average 80% if her previous test scores were 78, 88, 83, and 81?
Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
(78+88+83+81+x)/5=80
(330+x)/5=80
330+x=5*80
330+x=400
x=400-330
x=70 ans. for the last test score.
Proof:
(78+88+83+81+70)/5=80
400/5=80
80=80