Question

Sasha has some pennies, nickels, and dimes in her pocket. The number of coins is 16. The expression 0.01p+0.05n+0.10d represents the value of the coins, which is $1.22. She has twice as many nickles as pennies. How many of each coin does Sasha have?

Answer 1

I would like to use cents

p+n+d=16
1p+5n+10d=122
twice as many nicklese a pennies, n=2p

sub 2p for n
p+2p+d=16
1p+5(2p)+10d=122
simplified
3p+d=16
1p+10p+10d=122

3p+d=16
11p+10d=122
now solve
use subsitution

3p+d=16
minus 3p from both sides
d=16-3p
sub 16-3p for d in other equation

11p+10(16-3p)=122
11p+160-30p=122
160-19p=122
minus 160 both sides
-19p=-38
divide both sides by -19
p=2

sub back
n=2p
n=2(2)
n=4

d=16-3p
d=16-3(2)
d=16-6
d=10


2 pennies
4 nickles
10 dimes