Question

William has $12.80 in coins to be deposited in the bank. There are 3 times as many quarters as nickels and 20 more dimes than nickels. If n represents the number of nickels, what equation could be used to find the number of nickels to be deposited.

Answer 1

Let the number of nickels be = n

Let the number of dimes be = d

Let the number of quarter be = q

Total money William has = $12.80

As given, there are 3 times as many quarters as nickels

$q=3n$

And 20 more dimes than nickels

$d=20+n$

As total money is $12.80

$0.05n+0.10d+0.25q=12.80$

Putting the values of 'q' and 'd' to find 'n'

$0.05n+0.10(20+n)+0.25(3n)=12.80$

$0.05n+2+0.10n+0.75n=12.80$

$0.90n+2=12.80$

$0.90n=10.80$

$n=12$

Hence the number of nickels are = 12

If you want to also find dime and quarter, then

$q=3n=3\times12=36$

$d=20+n=20+12=32$