⁵₈ of John's savings comprised of 20-cent coins and 50-cent coins. John used some 20-cent coins to purchase a marble. The number of 50-cent coins left was 25% more than the number of 20-cent coins left. Given that John had 30 more 50-cent coins than 20-cent coins left in the end, find the amount of money John spent on the marble.

	20-cent coins	50-cent coins
Before	5x5 = 25 u	3x5 = 15 u
Change	- 13 u
After	4x3 = 12 u	5x3 = 15 u

Fraction of John's savings that comprised of 50-cent coins
= 1 - ⁵₈
= ³₈

Number of 50-cents coins in the end in percentage
= 100% + 25%
= 125%

125% = ¹²⁵₁₀₀ = ⁵₄

Number of 50-cent coins remains unchanged. Make the number of 50-cent coins the same.  LCM of 3 and 5 is 15.

Number of more 50-cent coins than 20-cent coins
= 15 u - 12 u
= 3 u

3 u = 30

1 u = 30 ÷ 3 = 10

Number of 20-cent coins spent on the marble 
= 25 u - 12 u
= 13 u
= 13 x 10
= 130

Amount that John spent on the marble 
= 130 x 0.2
= $26

Answer(s): $26