SOLUTION: You have a 77 test average in Math. Your mom wants the average up to an 80. You've taken 3 tests and you only have one test left. What do you need to get on that last test to rai

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Question 726655:
You have a 77 test average in Math. Your mom wants the average up to an 80. You've taken 3 tests and you only have one test left. What do you need to get on that last test to raise your average to an 80?
Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
(3*77+X)/4=80
231+X=4*80
231+X=320
X=320-231
X=89 IS NEEDED ON THE 4 th. TEST TO AVERAGE 80.