SOLUTION: Elsa had scored 78,90,64, and 83 on previous exams. What score does she need to make her average 77?

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Question 864550: Elsa had scored 78,90,64, and 83 on previous exams. What score does she need to make her average 77?
Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
(78+90+64+83+X)/5=77
(315+X)/5=77
315+X=77*5
315+X=385
X=385-315
X=70 REQUIRED FOR THE 5 TH TEST TO AVERAGE 77.