Question

A boy has twice as many nickels as he has pennies, and he has 5 less dimes than nickels. If he has $4.46 in all, how many coins of each kind does he have?

Answer 1

n=2p
n/2=p

n-5=d

10d+5n+1p=446
subsitute n/2 for p
subsitute n-5 for d
10(n-5)+5n+n/2=446
times 2 both sides
20(n-5)+10n+n=892
expand
20n-100+10n+n=892
31n-100=892
add 100 both sides
31n=992
divide both sides by 31
n=32

subsitute back

n/2=p
32/2=16=p


n-5=d
32-5=d=27


27 dimes
16 pennies
32 nickles