Riordan has 8 more 50-cent coins than 10-cent coins. After he used 17 of his 50-cent coins, the total value of 50-cent coins is $4.30 more than the total value of 10-cent coins. How many coins did he have in the end?
|
50¢ |
10¢ |
Before |
1 u + 8 |
1 u |
Change |
- 17 |
|
After |
1 u - 9 |
1 u |
|
50¢ |
10¢ |
Number |
1 u - 9 |
1 u |
Value |
50 |
10 |
Total value |
50 u - 450 |
10 u |
$1 = 100¢
$4.30 = 430¢
Number of 50¢ coins in the end
= 1 u + 8 - 17
= 1 u - 9
Total value of 50¢ coins in the end
= 50 x (1 u - 9)
= 50 u - 450
Total value of 10¢ coins in the end
= 10 x 1 u
= 10 u
After using 17 50-cent coins, the value of 50-cent coins is 430¢ more than the value of 10-cent coins. If another 430¢ is added to the 10-cent coins, the total value of 50-cent coins and 10-cent coins will be the same.
50 u - 450 = 10 u + 430
50 u - 10 u = 430 + 450
40 u = 880
1 u = 880 ÷ 40 = 22
Number of coins that Riordan had in the end
= 1 u + 1 u - 9
= 2 u - 9
= (2 x 22) - 9
= 44 - 9
= 35
Answer(s): 35