Natalie and Risa have some tarts each. If Natalie gives Risa 25 tarts, Natalie will have ⁵₈ as many tarts as Risa. If Natalie gives Risa 20 tarts, they will have an equal number of tarts. How many tarts does Natalie have at first?

	Case 1		Case 2
	Natalie	Risa	Natalie	Risa
Before	5 u + 25	8 u - 25	6.5 u + 20	6.5 u - 20
Change	- 25	+ 25	- 20	+ 20
After	5 u	8 u	6.5 u	6.5 u

Total number of tarts that Natalie and Risa have
= 5 u + 8 u
= 13 u 

Number of tarts that Natalie and Risa each has in the end is the same.

Number of tarts that Natalie and Risa each has in the end in Case 2
= 13 u ÷ 2
= 6.5 u

Number of tarts that Natalie had at first is the same in Case 1 and Case 2.

6.5 u + 20 = 5 u + 25
6.5 u - 5 u = 25 - 20
0.5 u = 5

1 u = 5 ÷ 0.5 = 10

Number of tarts that Natalie has
= 5 u + 25
= 5 x 10 + 25
= 50 + 25
= 75

Answer(s): 75