The average number of mangosteens in Box T, Box U and Box V is 28 and it is 8 more than the average number of oranges in the 3 boxes. ¹₅ of the oranges are in Box T and the oranges in Box T is 80% of the number of oranges in Box U. If each box has the same number of fruits, what percentage of the fruits in Box V are mangosteens?
Average number of oranges
= 28 - 8
= 20

Total number of oranges
= 3 x 20
= 60

Total number of mangosteens
= 3 x 28 
= 84

Total number of fruits
= 60 + 84
= 144

Number of fruits in each box
= 144 ÷ 3
= 48

Oranges in Box T	Oranges in Box U	Oranges in Box V	Total oranges
1x4	4x4		5x4
4x1	5x1
4 u	5 u	11 u	20 u

80% = ⁸⁰₁₀₀ = ⁴₅

The number of oranges in Box T is repeated.  Make the number of oranges in Box T the same.  LCM of 1 and 4 is 4. 

Total number of oranges
= 4 u + 5 u + 11 u
= 20 u

20 u = 60

1 u = 60 ÷ 20 = 3

Number of oranges in Box V
= 11 u
= 11 x 3
= 33

Number of mangosteens in Box V
= 48 - 33
= 15

Percentage of the fruits in Box V are mangosteens
= ¹⁵₄₈ x 100%
= 31.25%

Answer(s): 31.25%