⁵₉ of Jack's savings comprised of 10-cent coins and 20-cent coins. Jack used some 10-cent coins to purchase a kitchen set. The number of 20-cent coins left was 40% more than the number of 10-cent coins left. Given that Jack had 64 more 20-cent coins than 10-cent coins left in the end, find the amount of money Jack spent on the kitchen set.

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

Fraction of Jack's savings that comprised of 20-cent coins
= 1 - ⁵₉
= ⁴₉

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 4 and 7 is 28.

Number of more 20-cent coins than 10-cent coins
= 28 u - 20 u
= 8 u

8 u = 64

1 u = 64 ÷ 8 = 8

Number of 10-cent coins spent on the kitchen set 
= 35 u - 20 u
= 15 u
= 15 x 8
= 120

Amount that Jack spent on the kitchen set 
= 120 x 0.1
= $12

Answer(s): $12