The average weight of Tushar, Salil and Mukund is 46 kg. If the average weight of Tushar and Salil be 40 kg and that of Salil and Mukund be 46 kg, then the weight of Salil (in kg) is:

Correct option is A

Given: 
Average weight of Tushar, Salil and Mukund = 46 kg
Average weight of Tushar and Salil = 40 kg
Average of Salil and Mukund = 46 kg
Solution:
$$\frac{T + S + M}{3} = 46 \quad\Rightarrow\quad T + S + M = 138\\\ \\\frac{T + S}{2} = 40 \quad\Rightarrow\quad T + S = 80\\\ \\\frac{S + M}{2} = 46 \quad\Rightarrow\quad S + M = 92$$​​
Add (T + S) + (S + M) = 80 + 92 = 172 => T + 2S + M = 172
But T + S + M = 138 => subtracting gives S = 172 − 138 = 34
So Salil’s weight = 34 kg.
Exam Hall Method: