The number of five-cent coins in a pouch was
15 the number of twenty-cent coins. Will took out 23 twenty-cent coins and exchanged them for five-cent coins. Then he put the money back into the pouch. The number of twenty-cent coins became
25 the number of five-cent coins. How much money was there in the pouch?
|
Make u the same (1)x5 = (3) |
5-cent (1) |
20-cent (2) |
Before |
5 u |
1 u |
5 u |
Change |
+ 460 |
+ 92 |
- 23 |
After |
25 p |
5 p |
2 p |
Value of 20-cent coins to be exchanged to 5-cent coins
= 23 x 20
= 460
Number of 5-cent coins to be exchanged from the 20-cent coins
= 460 ÷ 5
= 92
(3) = (2)
25 p - 460 = 2 p + 23
25 p - 2 p = 23 + 460
23 p = 483
1 p = 483 ÷ 23 = 21
Number of 5-cent coins in the end
= 5 p
= 5 p x 21
= 105
Value of 5-cent coins in the end
= 105 x 5
= 525¢
Number of 20-cent coins in the end
= 2 p
= 2 x 21
= 42
Value of 20-cent coins in the end
= 42 x 20
= 840¢
Total value of coins
= 525 + 840
= 1365¢
$1 = 100¢
1365¢ = $13.65
Answer(s): $13.65