¹₂ of Xavier's savings comprised of 5-cent coins and 20-cent coins. Xavier used some 5-cent coins to purchase a flying saucer. The number of 20-cent coins left was 40% more than the number of 5-cent coins left. Given that Xavier had 40 more 20-cent coins than 5-cent coins left in the end, find the amount of money Xavier spent on the flying saucer.

	5-cent coins	20-cent coins
Before	1x7 = 7 u	1x7 = 7 u
Change	- 2 u
After	5x1 = 5 u	7x1 = 7 u

Fraction of Xavier's savings that comprised of 20-cent coins
= 1 - ¹₂
= ¹₂

Number of 20-cents coins in the end in percentage
= 100% + 40%
= 140%

140% = ¹⁴⁰₁₀₀ = ⁷₅

Number of 20-cent coins remains unchanged. Make the number of 20-cent coins the same.  LCM of 1 and 7 is 7.

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

2 u = 40

1 u = 40 ÷ 2 = 20

Number of 5-cent coins spent on the flying saucer 
= 7 u - 5 u
= 2 u
= 2 x 20
= 40

Amount that Xavier spent on the flying saucer 
= 40 x 0.05
= $2

Answer(s): $2