There are a total of 330 pieces of 5-cent coins, 10-cent coins and 20-cent coins in Peter's tin can.
35 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 Peter's tin can?
(a)
Number of 5-cent coins
=
35 x 330
= 198
Number of 10-cent coins and 20-cent coins
= 330 - 198
= 132
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 = 132
1 u = 132 ÷ 4 = 33
Number of 20-cent coins
= 3 u
= 3 x 33
= 99
(b)
100¢ = $1
Total value of the 20-cent coins in Peter's tin can
= 99 x 20
= 1980¢
= $19.80
Answer(s): (a) 99; (b) $19.80