SOLUTION: if my average in the 1st nine weeks was an 80 and my 2nd nine weeks was an 77 whats my average

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Question 696917: if my average in the 1st nine weeks was an 80 and my 2nd nine weeks was an 77 whats my average
Answer by lynnlo(4176) About Me  (Show Source):
You can put this solution on YOUR website!
first 9wks.=========80 80x9=720
ext 9 wks.=========77 77x9=693
add;720+693========1413divide 18 wks. by 1413=an average of 78.5