Lee has 8 more 20-cent coins than 5-cent coins. After he used 12 of his 20-cent coins, the total value of 20-cent coins is $4.30 more than the total value of 5-cent coins. How many coins did he have in the end?
|
20¢ |
5¢ |
Before |
1 u + 8 |
1 u |
Change |
- 12 |
|
After |
1 u - 4 |
1 u |
|
20¢ |
5¢ |
Number |
1 u - 4 |
1 u |
Value |
20 |
5 |
Total value |
20 u - 80 |
5 u |
$1 = 100¢
$4.30 = 430¢
Number of 20¢ coins in the end
= 1 u + 8 - 12
= 1 u - 4
Total value of 20¢ coins in the end
= 20 x (1 u - 4)
= 20 u - 80
Total value of 5¢ coins in the end
= 5 x 1 u
= 5 u
After using 12 20-cent coins, the value of 20-cent coins is 430¢ more than the value of 5-cent coins. If another 430¢ is added to the 5-cent coins, the total value of 20-cent coins and 5-cent coins will be the same.
20 u - 80 = 5 u + 430
20 u - 5 u = 430 + 80
15 u = 510
1 u = 510 ÷ 15 = 34
Number of coins that Lee had in the end
= 1 u + 1 u - 4
= 2 u - 4
= (2 x 34) - 4
= 68 - 4
= 64
Answer(s): 64