SOLUTION: help! Sam has test grades of 75,77, and 69 on his first three algebra tests. If he wants an average of at least 80 after his fourth test, what are the possible scores he can make

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Question 882848: help!
Sam has test grades of 75,77, and 69 on his first three algebra tests. If he wants an average of at least 80 after his fourth test, what are the possible scores he can make on his fourth test?

Answer by JulietG(1812) About Me  (Show Source):
You can put this solution on YOUR website!
Four tests * a possible 100 on each test = 400
Score desired = .8 * 400 = 320
Points already earned = 75+77+69 = 221
Points needed to earn to achieve 80% average = 320-221 = 99