There are a total of 390 pieces of 5-cent coins, 20-cent coins and 50-cent coins in Carl's piggy bank.
35 of these coins are 5-cent coins. The number of 50-cent coins is thrice the number of 20-cent coins.
- How many 50-cent coins are there?
- What is the total value of the 50-cent coins in Carl's piggy bank?
(a)
Number of 5-cent coins
=
35 x 390
= 234
Number of 20-cent coins and 50-cent coins
= 390 - 234
= 156
Number of 20-cent coins = 1 u
Number of 50-cent coins = 3 u
Number of 20-cent coins
= 1 u + 3 u
= 4 u
4 u = 156
1 u = 156 ÷ 4 = 39
Number of 50-cent coins
= 3 u
= 3 x 39
= 117
(b)
100¢ = $1
Total value of the 50-cent coins in Carl's piggy bank
= 117 x 50
= 5850¢
= $58.50
Answer(s): (a) 117; (b) $58.50