There are a total of 120 pieces of 5-cent coins, 10-cent coins and 20-cent coins in Ian's glass jar.
23 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 glass jar?
(a)
Number of 5-cent coins
=
23 x 120
= 80
Number of 10-cent coins and 20-cent coins
= 120 - 80
= 40
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 = 40
1 u = 40 ÷ 5 = 8
Number of 20-cent coins
= 4 u
= 4 x 8
= 32
(b)
100¢ = $1
Total value of the 20-cent coins in Ian's glass jar
= 32 x 20
= 640¢
= $6.40
Answer(s): (a) 32; (b) $6.40