Question

Sarah has 284 coins in a piggy bank with a total value of $22.78. Sarah has 173 pennies, 5 more dimes than nickels, the rest are quarters. How many of each does Sarah have?

Answer 1

Let P = number of coins of pennies (1 penny = 1 cent)
Let N = number of coins of nickels (1 nickel = 5 cents)
Let D = number of coins of dimes (1 dime = 10 cents)
Let Q = number of coins of quarters (1 quarter = 25 cents)

a) P + N + D + Q = 284 coins, but P = 173 coins, then:
173 + N + D + Q =284 coins
(1)  N + D + Q = 111 coins

b) D = N + 5 OR D - N =5 coins
(2) D - N = 5 coins

c) Let's find the VALUE in CENTS of (1) that is N + D + Q = 111 coins
5N + 10D + 25 Q = 2,278 - 173 (1 PENNY)
(3) 5N + 10D + 25Q = 2105 cents
Now we have 3 equation with 3 variables:

(1)  N + D + Q = 111 coins
(2) D - N = 5 coins
(3) 5N + 10D + 25Q = 2105 cents
Solving it gives:
17 coins N ( x 5 = 85 cents)
22 coins D ( x 10 = 220 cents)
72 coins D ( x 25 = 1,800 cents)
and 173 P,
proof:
that makes a total of 85+2201800+172 =2,278 c or $22.78