Question 1091589: Carlos has a box of coins that he uses when playing poker with friends. The box currently contains 39 coins, consisting of pennies, dimes, and quarters. The number of pennies is equal to the number of dimes, and the total value is $3.90. How many of each denomination of coin does he have?
Found 3 solutions by jorel1380, MathTherapy, ikleyn:
Answer by jorel1380(3719)   (Show Source):
You can put this solution on YOUR website! Let p be pennies, d be dimes, and q be quarters. The number of pennies is equal to the number of dimes, so p=d. Then:
p+d+q=39
2p+q=39 and
1p+10d+25q=390
1p+10p+25q=390
So:
2p+q=39
11p+25q=390
Then solve for p and q. ☺☺☺☺
Answer by MathTherapy(10556)  (Show Source):
You can put this solution on YOUR website!
Carlos has a box of coins that he uses when playing poker with friends. The box currently contains 39 coins, consisting of pennies, dimes, and quarters. The number of pennies is equal to the number of dimes, and the total value is $3.90. How many of each denomination of coin does he have?
Let number of dimes be D, and quarters, Q
Then number of pennies also = D
We then get: D + D + Q = 39______2D + Q = 39_____Q = 39 - 2D ------ eq (i)
Also, .01D + .1D + .25Q = 3.9_____.11D + .25Q = 3.9_____-eq (ii)
.11D + .25(39 - 2D) = 3.9 ------ Substituting 39 - 2D for Q in eq (ii)
.11D + 9.75 - .5D = 3.9
.11D - .5D = 3.9 - 9.75
- .39D = - 5.85
D, or number of dimes/number of pennies = 
Number of quarters: 
Answer by ikleyn(52866)  (Show Source):
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