The number of five-cent coins in a bottle was
13 the number of twenty-cent coins. Peter took out 25 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
25 the number of five-cent coins. How much money was there in the bottle?
|
Make u the same (1)x3 = (3) |
5-cent (1) |
20-cent (2) |
Before |
3 u |
1 u |
3 u |
Change |
+ 300 |
+ 100 |
- 25 |
After |
15 p |
5 p |
2 p |
Value of 20-cent coins to be exchanged to 5-cent coins
= 25 x 20
= 500
Number of 5-cent coins to be exchanged from the 20-cent coins
= 500 ÷ 5
= 100
(3) = (2)
15 p - 300 = 2 p + 25
15 p - 2 p = 25 + 300
13 p = 325
1 p = 325 ÷ 13 = 25
Number of 5-cent coins in the end
= 5 p
= 5 p x 25
= 125
Value of 5-cent coins in the end
= 125 x 5
= 625¢
Number of 20-cent coins in the end
= 2 p
= 2 x 25
= 50
Value of 20-cent coins in the end
= 50 x 20
= 1000¢
Total value of coins
= 625 + 1000
= 1625¢
$1 = 100¢
1625¢ = $16.25
Answer(s): $16.25