⁴₇ of Neave's savings comprised of 20-cent coins and 10-cent coins. Neave used some 20-cent coins to purchase a frisbee. The number of 10-cent coins left was 40% more than the number of 20-cent coins left. Given that Neave had 30 more 10-cent coins than 20-cent coins left in the end, find the amount of money Neave spent on the frisbee.

	20-cent coins	10-cent coins
Before	4x7 = 28 u	3x7 = 21 u
Change	- 13 u
After	5x3 = 15 u	7x3 = 21 u

Fraction of Neave's savings that comprised of 10-cent coins
= 1 - ⁴₇
= ³₇

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 3 and 7 is 21.

Number of more 10-cent coins than 20-cent coins
= 21 u - 15 u
= 6 u

6 u = 30

1 u = 30 ÷ 6 = 5

Number of 20-cent coins spent on the frisbee 
= 28 u - 15 u
= 13 u
= 13 x 5
= 65

Amount that Neave spent on the frisbee 
= 65 x 0.2
= $13

Answer(s): $13