Tommy has 9 more 20-cent coins than 10-cent coins. After he used 14 of his 20-cent coins, the total value of 20-cent coins is $1.90 more than the total value of 10-cent coins. How many coins did he have in the end?
| |
20¢ |
10¢ |
| Before |
1 u + 9 |
1 u |
| Change |
- 14 |
|
| After |
1 u - 5 |
1 u |
| |
20¢ |
10¢ |
| Number |
1 u - 5 |
1 u |
| Value |
20 |
10 |
| Total value |
20 u - 100 |
10 u |
$1 = 100¢
$1.90 = 190¢
Number of 20¢ coins in the end
= 1 u + 9 - 14
= 1 u - 5
Total value of 20¢ coins in the end
= 20 x (1 u - 5)
= 20 u - 100
Total value of 10¢ coins in the end
= 10 x 1 u
= 10 u
After using 14 20-cent coins, the value of 20-cent coins is 190¢ more than the value of 10-cent coins. If another 190¢ is added to the 10-cent coins, the total value of 20-cent coins and 10-cent coins will be the same.
20 u - 100 = 10 u + 190
20 u - 10 u = 190 + 100
10 u = 290
1 u = 290 ÷ 10 = 29
Number of coins that Tommy had in the end
= 1 u + 1 u - 5
= 2 u - 5
= (2 x 29) - 5
= 58 - 5
= 53
Answer(s): 53
