Daniel has 5 more 50-cent coins than 20-cent coins. After he used 9 of his 50-cent coins, the total value of 50-cent coins is $2.20 more than the total value of 20-cent coins. How many coins did he have at first?
|
50¢ |
20¢ |
Before |
1 u + 5 |
1 u |
Change |
- 9 |
|
After |
1 u - 4 |
1 u |
|
50¢ |
20¢ |
Number |
1 u - 4 |
1 u |
Value |
50 |
20 |
Total value |
50 u - 200 |
20 u |
$1 = 100¢
$2.20 = 220¢
Number of 50¢ coins in the end
= 1 u + 5 - 9
= 1 u - 4
Total value of 50¢ coins in the end
= 50 x (1 u - 4)
= 50 u - 200
Total value of 20¢ coins in the end
= 20 x 1 u
= 20 u
After using 9 50-cent coins, the value of 50-cent coins is 220¢ more than the value of 20-cent coins. If another 220¢ is added to the 20-cent coins, the total value of 50-cent coins and 20-cent coins will be the same.
50 u - 200 = 20 u + 220
50 u - 20 u = 220 + 200
30 u = 420
1 u = 420 ÷ 30 = 14
Number of coins that Daniel had at first
= 1 u + 1 u + 5
= 2 u + 5
= (2 x 14) + 5
= 28 + 5
= 33
Answer(s): 33