³₅ of Bobby's savings comprised of 20-cent coins and 10-cent coins. Bobby used some 20-cent coins to purchase a flying saucer. The number of 10-cent coins left was 50% more than the number of 20-cent coins left. Given that Bobby had 38 more 10-cent coins than 20-cent coins left in the end, find the amount of money Bobby spent on the flying saucer.

	20-cent coins	10-cent coins
Before	3x3 = 9 u	2x3 = 6 u
Change	- 5 u
After	2x2 = 4 u	3x2 = 6 u

Fraction of Bobby's savings that comprised of 10-cent coins
= 1 - ³₅
= ²₅

Number of 10-cents coins in the end in percentage
= 100% + 50%
= 150%

150% = ¹⁵⁰₁₀₀ = ³₂

Number of 10-cent coins remains unchanged. Make the number of 10-cent coins the same.  LCM of 2 and 3 is 6.

Number of more 10-cent coins than 20-cent coins
= 6 u - 4 u
= 2 u

2 u = 38

1 u = 38 ÷ 2 = 19

Number of 20-cent coins spent on the flying saucer 
= 9 u - 4 u
= 5 u
= 5 x 19
= 95

Amount that Bobby spent on the flying saucer 
= 95 x 0.2
= $19

Answer(s): $19