⁵₉ of Ben's savings comprised of 20-cent coins and 50-cent coins. Ben used some 20-cent coins to purchase a frisbee. The number of 50-cent coins left was 40% more than the number of 20-cent coins left. Given that Ben had 144 more 50-cent coins than 20-cent coins left in the end, find the amount of money Ben spent on the frisbee.

	20-cent coins	50-cent coins
Before	5x7 = 35 u	4x7 = 28 u
Change	- 15 u
After	5x4 = 20 u	7x4 = 28 u

Fraction of Ben's savings that comprised of 50-cent coins
= 1 - ⁵₉
= ⁴₉

Number of 50-cents coins in the end in percentage
= 100% + 40%
= 140%

140% = ¹⁴⁰₁₀₀ = ⁷₅

Number of 50-cent coins remains unchanged. Make the number of 50-cent coins the same.  LCM of 4 and 7 is 28.

Number of more 50-cent coins than 20-cent coins
= 28 u - 20 u
= 8 u

8 u = 144

1 u = 144 ÷ 8 = 18

Number of 20-cent coins spent on the frisbee 
= 35 u - 20 u
= 15 u
= 15 x 18
= 270

Amount that Ben spent on the frisbee 
= 270 x 0.2
= $54

Answer(s): $54