The number of five-cent coins in a bottle was ¹₅ the number of twenty-cent coins. Michael took out 20 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 ⁵₈ the number of five-cent coins. How much money was there in the bottle?

	Make u the same (1)x5 = (3)	5-cent (1)	20-cent (2)
Before	5 u	1 u	5 u
Change	+ 400	+ 80	- 20
After	40 p	8 p	5 p

Value of 20-cent coins to be exchanged to 5-cent coins
= 20 x 20
= 400

Number of 5-cent coins to be exchanged from the 20-cent coins
= 400 ÷ 5
= 80

(3) = (2)
40 p - 400 = 5 p + 20
40 p - 5 p = 20 + 400
35 p = 420

1 p = 420 ÷ 35 = 12

Number of 5-cent coins in the end
= 8 p
= 8 p x 12
= 96

Value of 5-cent coins in the end
= 96 x 5
= 480¢

Number of 20-cent coins in the end
= 5 p
= 5 x 12
= 60

Value of 20-cent coins in the end
= 60 x 20
= 1200¢

Total value of coins
= 480 + 1200
= 1680¢

$1 = 100¢
1680¢ = $16.80 

Answer(s): $16.80