Peter has 6 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 $2.90 more than the total value of 5-cent coins. How many coins did he have in the end?
|
10¢ |
5¢ |
Before |
1 u + 6 |
1 u |
Change |
- 10 |
|
After |
1 u - 4 |
1 u |
|
10¢ |
5¢ |
Number |
1 u - 4 |
1 u |
Value |
10 |
5 |
Total value |
10 u - 40 |
5 u |
$1 = 100¢
$2.90 = 290¢
Number of 10¢ coins in the end
= 1 u + 6 - 10
= 1 u - 4
Total value of 10¢ coins in the end
= 10 x (1 u - 4)
= 10 u - 40
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 290¢ more than the value of 5-cent coins. If another 290¢ is added to the 5-cent coins, the total value of 10-cent coins and 5-cent coins will be the same.
10 u - 40 = 5 u + 290
10 u - 5 u = 290 + 40
5 u = 330
1 u = 330 ÷ 5 = 66
Number of coins that Peter had in the end
= 1 u + 1 u - 4
= 2 u - 4
= (2 x 66) - 4
= 132 - 4
= 128
Answer(s): 128