out of 40 coins, 16 are dimes. half of the remaining coins are quarters and the rest are pennies and nickles. these are 2 nickles for every penny. how many pennies are there?

Work Shown:

40 coins total

16 are dimes

40-16 = 24 coins are not dimes

Half of this is 24*(1/2) = 12 which are quarters. The other half (12) are pennies and nickels

n = number of nickels

p = number of pennies

This means n+p = 12 so that we have 12 pennies and nickels combined.

"There are 2 nickels for every penny", so we can write n = 2p. If p = 1, then n = 2. If p = 2, then n = 4, etc. Whatever p is, we double it to get n.

So,

n+p = 12

2p+p = 12

3p = 12

p = 12/3

p = 4, we have 4 pennies

n = 2p

n = 2*4

n = 8 and 8 nickels

Here are all the coin counts

16+12+8+4 = 40 coins total