A collection of 30 coins worth 5.50 consists of nickels dimes and quarters there are twice as many dimes as nickeles how many quarters are there?

Answer 1

Let the number of nickels, dimes and quarters be n, d, q respectively. Then

n +d + q = 30

5n + 10d + 25q = 550

But d = 2n, so:

n + 2n + q = 30

=> 3n + q = 30

5n + 10(2n) + 25q = 550

=> 25n + 25q = 550

=> n + q = 22

Which gives two simultaneous equations to solve, resulting in:

n = 4, q = 18

So there are 18 quarters (plus 4 nickels and 8 dimes).