⁵₇ of Brandon's savings comprised of 20-cent coins and 10-cent coins. Brandon used some 20-cent coins to purchase a lego set. The number of 10-cent coins left was 40% more than the number of 20-cent coins left. Given that Brandon had 68 more 10-cent coins than 20-cent coins left in the end, find the amount of money Brandon spent on the lego set.

	20-cent coins	10-cent coins
Before	5x7 = 35 u	2x7 = 14 u
Change	- 25 u
After	5x2 = 10 u	7x2 = 14 u

Fraction of Brandon's savings that comprised of 10-cent coins
= 1 - ⁵₇
= ²₇

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 2 and 7 is 14.

Number of more 10-cent coins than 20-cent coins
= 14 u - 10 u
= 4 u

4 u = 68

1 u = 68 ÷ 4 = 17

Number of 20-cent coins spent on the lego set 
= 35 u - 10 u
= 25 u
= 25 x 17
= 425

Amount that Brandon spent on the lego set 
= 425 x 0.2
= $85

Answer(s): $85