Rael has 4 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 $3.70 more than the total value of 10-cent coins. How many coins did he have in the end?
|
20¢ |
10¢ |
Before |
1 u + 4 |
1 u |
Change |
- 16 |
|
After |
1 u - 12 |
1 u |
|
20¢ |
10¢ |
Number |
1 u - 12 |
1 u |
Value |
20 |
10 |
Total value |
20 u - 240 |
10 u |
$1 = 100¢
$3.70 = 370¢
Number of 20¢ coins in the end
= 1 u + 4 - 16
= 1 u - 12
Total value of 20¢ coins in the end
= 20 x (1 u - 12)
= 20 u - 240
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 370¢ more than the value of 10-cent coins. If another 370¢ is added to the 10-cent coins, the total value of 20-cent coins and 10-cent coins will be the same.
20 u - 240 = 10 u + 370
20 u - 10 u = 370 + 240
10 u = 610
1 u = 610 ÷ 10 = 61
Number of coins that Rael had in the end
= 1 u + 1 u - 12
= 2 u - 12
= (2 x 61) - 12
= 122 - 12
= 110
Answer(s): 110