The average weight of Amit, Gopal and Akshay is 45 kg. If the average weight of Amit and Gopal be 43 kg and that of Gopal and Akshay be 47 kg, then the weight of Gopal (in kg) is:

Correct option is D

Given:
The average weight of Amit, Gopal, and Akshay is 45 kg.
The average weight of Amit and Gopal is 43 kg.
The average weight of Gopal and Akshay is 47 kg.
Solution:
Let the weights of Amit, Gopal, and Akshay be A, G, and K respectively.
Sum of  weight of Amit, Gopal, and Akshay is 
( A + G + K) = 45 × 3 = 135 (Equation 1)
Sum of weight of Amit and Gopal is
(A + G) = 43 × 2 = 86 (Equation 2)
Sum of weight of Gopal and Akshay is
G + K = 47 × 2 = 94 (Equation 3)
Add equation 2 and 3 and then subtract from 1
Weight of Gopal = [(A+G) + (G+K) - (A+G+K)] = [94+86- 135] = 45 kg