Madi has $8.80 in pennies and nickels.

If there are twice as many nickels as pennies, how many pennies and nickels does Madi have?

0.01p + 0.05n = 8.80; n=? P

Let p = number of pennies.

Let n = number of nickels.

We are given that n = 2p and the total value is $8.80.

We know that a penny = $0.01 and that a nickel = $0.05.

So $0.01p + $0.05n = $8.80.

Substitute 2p for n:

$0.01p + $0.05*2p = $8.80

$0.01p + $0.10p = $8.80

$0.11p = $8.80

p = 80

So n = 2p = 2*80 = 160

Thus there are 80 pennies ($0.8) and 160 nickels ($8.00). The value of all the coins is $8.80.