The number of five-cent coins in a bottle was
14 the number of twenty-cent coins. Luke took out 24 twenty-cent coins and exchanged them for five-cent coins. Then he put the money back into the bottle. The number of twenty-cent coins became
35 the number of five-cent coins. How much money was there in the bottle?
|
Make u the same (1)x4 = (3) |
5-cent (1) |
20-cent (2) |
Before |
4 u |
1 u |
4 u |
Change |
+ 384 |
+ 96 |
- 24 |
After |
20 p |
5 p |
3 p |
Value of 20-cent coins to be exchanged to 5-cent coins
= 24 x 20
= 480
Number of 5-cent coins to be exchanged from the 20-cent coins
= 480 ÷ 5
= 96
(3) = (2)
20 p - 384 = 3 p + 24
20 p - 3 p = 24 + 384
17 p = 408
1 p = 408 ÷ 17 = 24
Number of 5-cent coins in the end
= 5 p
= 5 p x 24
= 120
Value of 5-cent coins in the end
= 120 x 5
= 600¢
Number of 20-cent coins in the end
= 3 p
= 3 x 24
= 72
Value of 20-cent coins in the end
= 72 x 20
= 1440¢
Total value of coins
= 600 + 1440
= 2040¢
$1 = 100¢
2040¢ = $20.40
Answer(s): $20.40