A store owner has 20 more starfruits than mangosteens. After he sold 75% of the starfruits and 30% of the mangosteens, he is left with 40 less starfruits than mangosteens. What fraction of the fruits left were mangosteens?

	Starfruits		Mangosteens
Comparing starfruits and mangosteens at first	20 more
Before	4x5 = 20 u	+ 20	10x2 = 20 u
Change	- 3x5 = - 15 u	- 15	- 3x2 = - 6 u
After	1x5 = 5 u	+ 5	7x2 = 14 u
Comparing starfruits  and mangosteens in the end	40 less

75% = ⁷⁵₁₀₀ = ³₄ 
75% x 20 = ³₄ x 20 = 15
20 - 15 = 5

30% = ³⁰₁₀₀ = ³₁₀ 

The number of starfruits is 40 less than the number of mangosteens in the end. So, if another 40 starfruits are added, the number of starfruits and mangosteens in the end will be the same.

5 u + 5 + 40 = 14 u
5 u + 45 = 14 u
14 u - 5 u = 45
9 u = 45

1 u = 45 ÷ 9 = 5

Number of mangosteens left
= 14 u
= 14 x 5
= 70

Total number of fruits left
= 5 u + 5 + 14 u
= 19 u + 5
= 19 x 5 + 5
= 95 + 5
= 100

^{Mangosteens left}_{Total fruits left} = ⁷⁰₁₀₀ = ⁷₁₀

Answer(s): ⁷₁₀