Acoin 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

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