There are a total of 180 pieces of 5-cent coins, 10-cent coins and 20-cent coins in Pierre's piggy bank.
25 of these coins are 5-cent coins. The number of 20-cent coins is twice the number of 10-cent coins.
- How many 20-cent coins are there?
- What is the total value of the 20-cent coins in Pierre's piggy bank?
(a)
Number of 5-cent coins
=
25 x 180
= 72
Number of 10-cent coins and 20-cent coins
= 180 - 72
= 108
Number of 10-cent coins = 1 u
Number of 20-cent coins = 2 u
Number of 10-cent coins
= 1 u + 2 u
= 3 u
3 u = 108
1 u = 108 ÷ 3 = 36
Number of 20-cent coins
= 2 u
= 2 x 36
= 72
(b)
100¢ = $1
Total value of the 20-cent coins in Pierre's piggy bank
= 72 x 20
= 1440¢
= $14.40
Answer(s): (a) 72; (b) $14.40