A coin bank contains twice as many nickels as dimes and five times as many pennies as dimes. The value of the collection is $2.00 or 200cents. How many pennies, nickels, and dimes are in the collection?

N=number of nickles

d=number of dimes

p=number of pennies

so we have

"twice as many nickles as dimes"

n=2d

"five times as many pennies as dimes"

p=5d

we know that the total value is 200 cents

value=5n+10d+1p

200=5n+10d+p

we know that

n=2d

p=5d

sub those for n and p

200=5 (2d) + 10d+5d

200=10d+10d+5d

200=25d

divide both sides by 25

8=d

there are 8 dimes

easy, sub

n=2d

n=2 (8)

n=16

16 nickles

p=5d

p=5 (8)

P=40

40 pennies

40 pennies

16 nicles

8 dimes