There are a total of 210 pieces of 5-cent coins, 10-cent coins and 20-cent coins in Ian's piggy bank.
37 of these coins are 5-cent coins. The number of 20-cent coins is four times the number of 10-cent coins.
- How many 20-cent coins are there?
- What is the total value of the 20-cent coins in Ian's piggy bank?
(a)
Number of 5-cent coins
=
37 x 210
= 90
Number of 10-cent coins and 20-cent coins
= 210 - 90
= 120
Number of 10-cent coins = 1 u
Number of 20-cent coins = 4 u
Number of 10-cent coins
= 1 u + 4 u
= 5 u
5 u = 120
1 u = 120 ÷ 5 = 24
Number of 20-cent coins
= 4 u
= 4 x 24
= 96
(b)
100¢ = $1
Total value of the 20-cent coins in Ian's piggy bank
= 96 x 20
= 1920¢
= $19.20
Answer(s): (a) 96; (b) $19.20