The number of ten-cent coins in a pouch was ¹₃ the number of twenty-cent coins. Oliver took out 19 twenty-cent coins and exchanged them for ten-cent coins. Then he put the money back into the pouch. The number of twenty-cent coins became ⁵₈ the number of ten-cent coins. How much money was there in the pouch?

	Make u the same (1)x3 = (3)	10-cent (1)	20-cent (2)
Before	3 u	1 u	3 u
Change	+ 114	+ 38	- 19
After	24 p	8 p	5 p

Value of 20-cent coins to be exchanged to 10-cent coins
= 19 x 20
= 380

Number of 10-cent coins to be exchanged from the 20-cent coins
= 380 ÷ 10
= 38

(3) = (2)
24 p - 114 = 5 p + 19
24 p - 5 p = 19 + 114
19 p = 133

1 p = 133 ÷ 19 = 7

Number of 10-cent coins in the end
= 8 p
= 8 p x 7
= 56

Value of 10-cent coins in the end
= 56 x 10
= 560¢

Number of 20-cent coins in the end
= 5 p
= 5 x 7
= 35

Value of 20-cent coins in the end
= 35 x 20
= 700¢

Total value of coins
= 560 + 700
= 1260¢

$1 = 100¢
1260¢ = $12.60 

Answer(s): $12.60