⁹₁₀ of Seth's savings comprised of 20-cent coins and 50-cent coins. Seth used some 20-cent coins to purchase a flying saucer. The number of 50-cent coins left was 40% more than the number of 20-cent coins left. Given that Seth had 40 more 50-cent coins than 20-cent coins left in the end, find the amount of money Seth spent on the flying saucer.

	20-cent coins	50-cent coins
Before	9x7 = 63 u	1x7 = 7 u
Change	- 58 u
After	5x1 = 5 u	7x1 = 7 u

Fraction of Seth's savings that comprised of 50-cent coins
= 1 - ⁹₁₀
= ¹₁₀

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 1 and 7 is 7.

Number of more 50-cent coins than 20-cent coins
= 7 u - 5 u
= 2 u

2 u = 40

1 u = 40 ÷ 2 = 20

Number of 20-cent coins spent on the flying saucer 
= 63 u - 5 u
= 58 u
= 58 x 20
= 1160

Amount that Seth spent on the flying saucer 
= 1160 x 0.2
= $232

Answer(s): $232