There are a total of 170 pieces of 5-cent coins, 10-cent coins and 20-cent coins in Pierre's coin box.
25 of these coins are 5-cent coins. The number of 20-cent coins is twice the number of 10-cent coins.
- How many 20-cent coins are there?
- What is the total value of the 20-cent coins in Pierre's coin box?
(a)
Number of 5-cent coins
=
25 x 170
= 68
Number of 10-cent coins and 20-cent coins
= 170 - 68
= 102
Number of 10-cent coins = 1 u
Number of 20-cent coins = 2 u
Number of 10-cent coins
= 1 u + 2 u
= 3 u
3 u = 102
1 u = 102 ÷ 3 = 34
Number of 20-cent coins
= 2 u
= 2 x 34
= 68
(b)
100¢ = $1
Total value of the 20-cent coins in Pierre's coin box
= 68 x 20
= 1360¢
= $13.60
Answer(s): (a) 68; (b) $13.60