⁵₈ of Bobby's savings comprised of 5-cent coins and 10-cent coins. Bobby used some 5-cent coins to purchase a board game. The number of 10-cent coins left was 40% more than the number of 5-cent coins left. Given that Bobby had 24 more 10-cent coins than 5-cent coins left in the end, find the amount of money Bobby spent on the board game.

	5-cent coins	10-cent coins
Before	5x7 = 35 u	3x7 = 21 u
Change	- 20 u
After	5x3 = 15 u	7x3 = 21 u

Fraction of Bobby's savings that comprised of 10-cent coins
= 1 - ⁵₈
= ³₈

Number of 10-cents coins in the end in percentage
= 100% + 40%
= 140%

140% = ¹⁴⁰₁₀₀ = ⁷₅

Number of 10-cent coins remains unchanged. Make the number of 10-cent coins the same.  LCM of 3 and 7 is 21.

Number of more 10-cent coins than 5-cent coins
= 21 u - 15 u
= 6 u

6 u = 24

1 u = 24 ÷ 6 = 4

Number of 5-cent coins spent on the board game 
= 35 u - 15 u
= 20 u
= 20 x 4
= 80

Amount that Bobby spent on the board game 
= 80 x 0.05
= $4

Answer(s): $4