There are a total of 180 pieces of 5-cent coins, 10-cent coins and 20-cent coins in Simon's piggy bank.
45 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 Simon's piggy bank?
(a)
Number of 5-cent coins
=
45 x 180
= 144
Number of 10-cent coins and 20-cent coins
= 180 - 144
= 36
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 = 36
1 u = 36 ÷ 3 = 12
Number of 20-cent coins
= 2 u
= 2 x 12
= 24
(b)
100¢ = $1
Total value of the 20-cent coins in Simon's piggy bank
= 24 x 20
= 480¢
= $4.80
Answer(s): (a) 24; (b) $4.80