SOLUTION: Allen bought 30 stamps at the post office in 39¢ and 24¢ denominations. If the total cost of the stamps was $9.90, how many 39¢ stamps did Allen buy?
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Question 124934: Allen bought 30 stamps at the post office in 39¢ and 24¢ denominations. If the total cost of the stamps was $9.90, how many 39¢ stamps did Allen buy? Answer by checkley71(8403) (Show Source):
You can put this solution on YOUR website! .39X+.24(30-X)=9.90
.39X+7.20-.24X=9.90
.15X=9.90-7.20
.15X=2.70
X-2.70/.15
X=18 THE NUMBER OF $.39 STAMPS BOUGHT.
30-18=12 IS THE NUMBER OF $.24 STAMPS BOUGHT.
PROOF
.39*18+.24*12=9.90
7.02+2.88=9.90
9.90=9.90
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