SOLUTION: Ellen has a total of 100 coins in her jar. the coins inside the jar are either quarters or dimes. the total amount in the jar is $22.00, how many of each type of coin is in the jar

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Question 126084: Ellen has a total of 100 coins in her jar. the coins inside the jar are either quarters or dimes. the total amount in the jar is $22.00, how many of each type of coin is in the jar? Use Q for quarters and D for dimes.
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
Q+D=100 OR Q=100-D
.25Q+.10D=22
NOW REPLACE Q WITH 100-D & SOLVE FOR D
.25(100-D)+.10D=22
25-.25D+.10D=22
-.15D=22-25
-.15D=-3
D=-3/.15
D=20 IS THE NUMBER OF DIMES.
100-20=80 IS THE NUMBER OF QUARTERS.
PROOF
.25*80+.10*20=22
20+2=22
22=22