The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, what is the weight of B?	Options.
A) 28
B) 30
C) 32
D) 34
E) 31

Rationale: "let the weight of a , b and c are a , b and c respectively . average weight of a , b and c = 45 a + b + c = 45 × 3 = 135 - - - equation ( 1 ) average weight of a and b = 40 a + b = 40 × 2 = 80 - - - equation ( 2 ) average weight of b and c = 43 b + c = 43 × 2 = 86 - - - equation ( 3 ) equation ( 2 ) + equation ( 3 ) - equation ( 1 ) = > a + b + b + c - ( a + b + c ) = 80 + 86 - 135 = > b = 80 + 86 - 135 = 166 - 135 = 31 weight of b = 31 kg answer is e ."
Answer: E