Sean has 6 more 20-cent coins than 10-cent coins. After he used 16 of his 20-cent coins, the total value of 20-cent coins is $4.50 more than the total value of 10-cent coins. How many coins did he have at first?
|
20¢ |
10¢ |
Before |
1 u + 6 |
1 u |
Change |
- 16 |
|
After |
1 u - 10 |
1 u |
|
20¢ |
10¢ |
Number |
1 u - 10 |
1 u |
Value |
20 |
10 |
Total value |
20 u - 200 |
10 u |
$1 = 100¢
$4.50 = 450¢
Number of 20¢ coins in the end
= 1 u + 6 - 16
= 1 u - 10
Total value of 20¢ coins in the end
= 20 x (1 u - 10)
= 20 u - 200
Total value of 10¢ coins in the end
= 10 x 1 u
= 10 u
After using 16 20-cent coins, the value of 20-cent coins is 450¢ more than the value of 10-cent coins. If another 450¢ is added to the 10-cent coins, the total value of 20-cent coins and 10-cent coins will be the same.
20 u - 200 = 10 u + 450
20 u - 10 u = 450 + 200
10 u = 650
1 u = 650 ÷ 10 = 65
Number of coins that Sean had at first
= 1 u + 1 u + 6
= 2 u + 6
= (2 x 65) + 6
= 130 + 6
= 136
Answer(s): 136