A newspaper carrier has 620 in change He has ten more quarte

A newspaper carrier has $6.20 in change. He has ten more quarters than dimes but two times as many nickels as quarters. How many coins of each type does he have? How many dimes does he have?

Solution

d for dimes, n for nickels, and q for quarters.

q=10+d

n=2q

0.25q + 0.10d + 0.05n = 6.20

0.25(10+d)+0.10d+0.05(20+2d)=6.20

2.5+0.25d+0.10d+1+0.10d=6.20

0.45 d = 2.7

d=6

q=16

n=32