SOLUTION: Betty has a jar containing 70 coins all of which are either quarters or nickels. the total value of the coins is 7.50 how many of each type of coin does she have?

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Question 233816: Betty has a jar containing 70 coins all of which are either quarters or nickels. the total value of the coins is 7.50 how many of each type of coin does she have?
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
Q+N=70 OR Q=70-N
.25Q+.05N=7.50
.25(70-N)+.05N=7.50
17.5-.25N+.05N=7.50
-.20N=7.50-17.50
-.20N=-10
N=-10/-.20
N=50 NICKLES IN THE JAR.
Q+50=70
Q=70-50
Q=20 QUARTERS IN THE JAR.
PROOF:
.25*20+.05*50=7.50
5.00+2.50=7.50
7.50=7.50