Question 842692: a newspaper carrier has $3.35 in change. He has seven more quarters than dimes but two times as many nickles as quarters. How many coins of each does he have?
Answer by LinnW(1048)   (Show Source):
You can put this solution on YOUR website! set n = no of nickles
d = no of dimes
q = no of quarters
0.05(n) + 0.10(d) + 0.25(q) = 3.35
q = d + 7
n = 2q
So n = 2(d + 7)
n = 2d + 14
substitute in 0.05(n) + 0.10(d) + 0.25(q) = 3.35
0.05(2d + 14) + 0.10(d) + 0.25(d + 7) = 3.35
0.10d + 0.70 + 0.10d + 0.25d + 1.75 = 3.35
0.45d + 2.45 = 3.35
add -2.45 to each side
0.45d = 0.90
d = 2
since q = d + 7, q = 2 + 7 = 9
since q = 9 and n = 2q , n = 2(9) = 18
checking
0.05(18) + 0.10(2) + 0.25(9) =? 3.35
0.90 + 0.20 + 2.25 =? 3.35
3.35 = 3.35
so n = 18, d = 2, and q = 9
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