The average number of starfruits in Box R, Box S and Box T is 21 and it is 7 more than the average number of kiwis in the 3 boxes. ¹₇ of the kiwis are in Box R and the kiwis in Box R is 40% of the number of kiwis in Box S. If each box has the same number of fruits, what percentage of the fruits in Box T are starfruits?
Average number of kiwis
= 21 - 7
= 14

Total number of kiwis
= 3 x 14
= 42

Total number of starfruits
= 3 x 21 
= 63

Total number of fruits
= 42 + 63
= 105

Number of fruits in each box
= 105 ÷ 3
= 35

Kiwis in Box R	Kiwis in Box S	Kiwis in Box T	Total kiwis
1x2	6x2		7x2
2x1	5x1
2 u	5 u	7 u	14 u

40% = ⁴⁰₁₀₀ = ²₅

The number of kiwis in Box R is repeated.  Make the number of kiwis in Box R the same.  LCM of 1 and 2 is 2. 

Total number of kiwis
= 2 u + 5 u + 7 u
= 14 u

14 u = 42

1 u = 42 ÷ 14 = 3

Number of kiwis in Box T
= 7 u
= 7 x 3
= 21

Number of starfruits in Box T
= 35 - 21
= 14

Percentage of the fruits in Box T are starfruits
= ¹⁴₃₅ x 100%
= 40%

Answer(s): 40%