The average weight of A, B and C is 43 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then the weight of B is:  Choose the correct choice from the following choices.
A) 33 kg B) 31 kg C) 32 kg D) 36 kg E) 37 kg
Let A, B, C represent their respective weights.   Then, we have: A + B + C = (45 x 3) = 129 .... (i)   A + B = (40 x 2) = 80 .... (ii)   B + C = (43 x 2) = 86 ....(iii)   Adding (ii) and (iii), we get: A + 2B + C = 166 .... (iv)   Subtracting (i) from (iv), we get : B = 37.   B's weight = 37 kg.   37 kg
<result>E</result>
The average weight of A, B and C is 43 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then the weight of B is: