A store owner has 36 more mangosteens than persimmons. After he sold 75% of the mangosteens and 35% of the persimmons, he is left with 15 less mangosteens than persimmons. What fraction of the fruits left were persimmons?

	Mangosteens		Persimmons
Comparing mangosteens and persimmons at first	36 more
Before	4x5 = 20 u	+ 36	20x1 = 20 u
Change	- 3x5 = - 15 u	- 27	- 7x1 = - 7 u
After	1x5 = 5 u	+ 9	13x1 = 13 u
Comparing mangosteens  and persimmons in the end	15 less

75% = ⁷⁵₁₀₀ = ³₄ 
75% x 36 = ³₄ x 36 = 27
36 - 27 = 9

35% = ³⁵₁₀₀ = ⁷₂₀ 

The number of mangosteens is 15 less than the number of persimmons in the end. So, if another 15 mangosteens are added, the number of mangosteens and persimmons in the end will be the same.

5 u + 9 + 15 = 13 u
5 u + 24 = 13 u
13 u - 5 u = 24
8 u = 24

1 u = 24 ÷ 8 = 3

Number of persimmons left
= 13 u
= 13 x 3
= 39

Total number of fruits left
= 5 u + 9 + 13 u
= 18 u + 9
= 18 x 3 + 9
= 54 + 9
= 63

^{Persimmons left}_{Total fruits left} = ³⁹₆₃ = ¹³₂₁

Answer(s): ¹³₂₁