There are a total of 360 pieces of 5-cent coins, 10-cent coins and 20-cent coins in John's piggy bank.
45 of these coins are 5-cent coins. The number of 20-cent coins is thrice the number of 10-cent coins.
- How many 20-cent coins are there?
- What is the total value of the 20-cent coins in John's piggy bank?
(a)
Number of 5-cent coins
=
45 x 360
= 288
Number of 10-cent coins and 20-cent coins
= 360 - 288
= 72
Number of 10-cent coins = 1 u
Number of 20-cent coins = 3 u
Number of 10-cent coins
= 1 u + 3 u
= 4 u
4 u = 72
1 u = 72 ÷ 4 = 18
Number of 20-cent coins
= 3 u
= 3 x 18
= 54
(b)
100¢ = $1
Total value of the 20-cent coins in John's piggy bank
= 54 x 20
= 1080¢
= $10.80
Answer(s): (a) 54; (b) $10.80