Money word problem

Question

Christopher's piggy bank contained $7.40 in nickels and pennies. If there were 80 more pennies than nickels, how many of each did he have in the piggy bank?

Answer 1

5n+p=740

p=80+n

p=740-5n

0= 660-6n

n=110 nickels

p= 190 pennies

Answer 2

Let n and p be the number of nickels and pennies.

p = n+80

0.01p + 0.05n = 7.40

Multiply both sides of the equal sign by 100

p+5n = 740

substituting for p

n+80 + 5n = 740

6n = 660

n = 660/6 = 110 nickels

p = n+80 = 190 pennies