Will has 5 more 50-cent coins than 20-cent coins. After he used 10 of his 50-cent coins, the total value of 50-cent coins is $3.20 more than the total value of 20-cent coins. How many coins did he have in the end?
| |
50¢ |
20¢ |
| Before |
1 u + 5 |
1 u |
| Change |
- 10 |
|
| After |
1 u - 5 |
1 u |
| |
50¢ |
20¢ |
| Number |
1 u - 5 |
1 u |
| Value |
50 |
20 |
| Total value |
50 u - 250 |
20 u |
$1 = 100¢
$3.20 = 320¢
Number of 50¢ coins in the end
= 1 u + 5 - 10
= 1 u - 5
Total value of 50¢ coins in the end
= 50 x (1 u - 5)
= 50 u - 250
Total value of 20¢ coins in the end
= 20 x 1 u
= 20 u
After using 10 50-cent coins, the value of 50-cent coins is 320¢ more than the value of 20-cent coins. If another 320¢ is added to the 20-cent coins, the total value of 50-cent coins and 20-cent coins will be the same.
50 u - 250 = 20 u + 320
50 u - 20 u = 320 + 250
30 u = 570
1 u = 570 ÷ 30 = 19
Number of coins that Will had in the end
= 1 u + 1 u - 5
= 2 u - 5
= (2 x 19) - 5
= 38 - 5
= 33
Answer(s): 33
