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

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) (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.
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