⁸₉ of Ryan's savings comprised of 20-cent coins and 50-cent coins. Ryan used some 20-cent coins to purchase a doll set. The number of 50-cent coins left was 40% more than the number of 20-cent coins left. Given that Ryan had 20 more 50-cent coins than 20-cent coins left in the end, find the amount of money Ryan spent on the doll set.

	20-cent coins	50-cent coins
Before	8x7 = 56 u	1x7 = 7 u
Change	- 51 u
After	5x1 = 5 u	7x1 = 7 u

Fraction of Ryan's savings that comprised of 50-cent coins
= 1 - ⁸₉
= ¹₉

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 = 20

1 u = 20 ÷ 2 = 10

Number of 20-cent coins spent on the doll set 
= 56 u - 5 u
= 51 u
= 51 x 10
= 510

Amount that Ryan spent on the doll set 
= 510 x 0.2
= $102

Answer(s): $102