Jeremy has 9 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 $2.70 more than the total value of 5-cent coins. How many coins did he have in the end?
|
20¢ |
5¢ |
Before |
1 u + 9 |
1 u |
Change |
- 12 |
|
After |
1 u - 3 |
1 u |
|
20¢ |
5¢ |
Number |
1 u - 3 |
1 u |
Value |
20 |
5 |
Total value |
20 u - 60 |
5 u |
$1 = 100¢
$2.70 = 270¢
Number of 20¢ coins in the end
= 1 u + 9 - 12
= 1 u - 3
Total value of 20¢ coins in the end
= 20 x (1 u - 3)
= 20 u - 60
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 270¢ more than the value of 5-cent coins. If another 270¢ is added to the 5-cent coins, the total value of 20-cent coins and 5-cent coins will be the same.
20 u - 60 = 5 u + 270
20 u - 5 u = 270 + 60
15 u = 330
1 u = 330 ÷ 15 = 22
Number of coins that Jeremy had in the end
= 1 u + 1 u - 3
= 2 u - 3
= (2 x 22) - 3
= 44 - 3
= 41
Answer(s): 41