⁶₇ of Oliver's savings comprised of 5-cent coins and 10-cent coins. Oliver used some 5-cent coins to purchase a kitchen set. The number of 10-cent coins left was 40% more than the number of 5-cent coins left. Given that Oliver had 40 more 10-cent coins than 5-cent coins left in the end, find the amount of money Oliver spent on the kitchen set.

	5-cent coins	10-cent coins
Before	6x7 = 42 u	1x7 = 7 u
Change	- 37 u
After	5x1 = 5 u	7x1 = 7 u

Fraction of Oliver's savings that comprised of 10-cent coins
= 1 - ⁶₇
= ¹₇

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 1 and 7 is 7.

Number of more 10-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 kitchen set 
= 42 u - 5 u
= 37 u
= 37 x 20
= 740

Amount that Oliver spent on the kitchen set 
= 740 x 0.05
= $37

Answer(s): $37