Ian has 2 more 10-cent coins than 5-cent coins. After he used 10 of his 10-cent coins, the total value of 10-cent coins is $4.70 more than the total value of 5-cent coins. How many coins did he have in the end?
|
10¢ |
5¢ |
Before |
1 u + 2 |
1 u |
Change |
- 10 |
|
After |
1 u - 8 |
1 u |
|
10¢ |
5¢ |
Number |
1 u - 8 |
1 u |
Value |
10 |
5 |
Total value |
10 u - 80 |
5 u |
$1 = 100¢
$4.70 = 470¢
Number of 10¢ coins in the end
= 1 u + 2 - 10
= 1 u - 8
Total value of 10¢ coins in the end
= 10 x (1 u - 8)
= 10 u - 80
Total value of 5¢ coins in the end
= 5 x 1 u
= 5 u
After using 10 10-cent coins, the value of 10-cent coins is 470¢ more than the value of 5-cent coins. If another 470¢ is added to the 5-cent coins, the total value of 10-cent coins and 5-cent coins will be the same.
10 u - 80 = 5 u + 470
10 u - 5 u = 470 + 80
5 u = 550
1 u = 550 ÷ 5 = 110
Number of coins that Ian had in the end
= 1 u + 1 u - 8
= 2 u - 8
= (2 x 110) - 8
= 220 - 8
= 212
Answer(s): 212