Risa, Tina and Zara had a sum of money. The amount of money Risa had was ³₅ of the amount of money Tina had. The ratio of the amount of money Tina had to the total amount of money Zara and Tina had was 3: 7. After Zara gave $85 to Tina, she had as much money as Tina. How much more money did Zara have than Risa in the end?

Risa	Tina	Zara
3x3 = 9 u	5x3 = 15 u
	3x5 = 15 u	4x5 = 20 u
9 u	15 u	20 u

The amount that Tina had is the repeated identity. Make the amount that Tina had the same.  LCM of 5 and 3 is 15.

	Risa	Tina	Zara
Before	9 u	15 u	20 u
Change	No change	+ 85	- 85
After	9 u	15 u + 85	20 u - 85

The amount that Zara and Tina had in the end is the same.

20 u - 85 = 15 u + 85
20 u - 15 u = 85 + 85 
5 u = 170

1 u = 170 ÷ 5 = 34

Amount that Zara had more than Risa in the end
= 20 u - 85 - 9 u
= 11 u - 85
= 11 x 34 - 85
= 374 - 85
= $289

Answer(s): $289