Brandon has 4 more 10-cent coins than 5-cent coins. After he used 9 of his 10-cent coins, the total value of 10-cent coins is $3.90 more than the total value of 5-cent coins. How many coins did he have at first?
|
10¢ |
5¢ |
Before |
1 u + 4 |
1 u |
Change |
- 9 |
|
After |
1 u - 5 |
1 u |
|
10¢ |
5¢ |
Number |
1 u - 5 |
1 u |
Value |
10 |
5 |
Total value |
10 u - 50 |
5 u |
$1 = 100¢
$3.90 = 390¢
Number of 10¢ coins in the end
= 1 u + 4 - 9
= 1 u - 5
Total value of 10¢ coins in the end
= 10 x (1 u - 5)
= 10 u - 50
Total value of 5¢ coins in the end
= 5 x 1 u
= 5 u
After using 9 10-cent coins, the value of 10-cent coins is 390¢ more than the value of 5-cent coins. If another 390¢ is added to the 5-cent coins, the total value of 10-cent coins and 5-cent coins will be the same.
10 u - 50 = 5 u + 390
10 u - 5 u = 390 + 50
5 u = 440
1 u = 440 ÷ 5 = 88
Number of coins that Brandon had at first
= 1 u + 1 u + 4
= 2 u + 4
= (2 x 88) + 4
= 176 + 4
= 180
Answer(s): 180