Luke has 3 more 20-cent coins than 10-cent coins. After he used 19 of his 20-cent coins, the total value of 20-cent coins is $4.40 more than the total value of 10-cent coins. How many coins did he have at first?
|
20¢ |
10¢ |
Before |
1 u + 3 |
1 u |
Change |
- 19 |
|
After |
1 u - 16 |
1 u |
|
20¢ |
10¢ |
Number |
1 u - 16 |
1 u |
Value |
20 |
10 |
Total value |
20 u - 320 |
10 u |
$1 = 100¢
$4.40 = 440¢
Number of 20¢ coins in the end
= 1 u + 3 - 19
= 1 u - 16
Total value of 20¢ coins in the end
= 20 x (1 u - 16)
= 20 u - 320
Total value of 10¢ coins in the end
= 10 x 1 u
= 10 u
After using 19 20-cent coins, the value of 20-cent coins is 440¢ more than the value of 10-cent coins. If another 440¢ is added to the 10-cent coins, the total value of 20-cent coins and 10-cent coins will be the same.
20 u - 320 = 10 u + 440
20 u - 10 u = 440 + 320
10 u = 760
1 u = 760 ÷ 10 = 76
Number of coins that Luke had at first
= 1 u + 1 u + 3
= 2 u + 3
= (2 x 76) + 3
= 152 + 3
= 155
Answer(s): 155