There are a total of 120 pieces of 5-cent coins, 10-cent coins and 20-cent coins in Ahmad's coin box.
58 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 Ahmad's coin box?
(a)
Number of 5-cent coins
=
58 x 120
= 75
Number of 10-cent coins and 20-cent coins
= 120 - 75
= 45
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 = 45
1 u = 45 ÷ 5 = 9
Number of 20-cent coins
= 4 u
= 4 x 9
= 36
(b)
100¢ = $1
Total value of the 20-cent coins in Ahmad's coin box
= 36 x 20
= 720¢
= $7.20
Answer(s): (a) 36; (b) $7.20