The average weight of A, B and C is 45 kg. If the average weight of A and B be 42 kg and that of B and C be 43 kg, then the weight of B is:	Select the correct option
A) 33 kg  B) 31 kg  C) 32 kg  D) 36 kg  E) 35 kg

Rationale: "let a , b , c represent their respective weights . then , we have : a + b + c = ( 45 x 3 ) = 135 . . . . ( i ) a + b = ( 42 x 2 ) = 84 . . . . ( ii ) b + c = ( 43 x 2 ) = 86 . . . . ( iii ) adding ( ii ) and ( iii ) , we get : a + 2 b + c = 170 . . . . ( iv ) subtracting ( i ) from ( iv ) , we get : b = 35 b ' s weight = 35 kg . e"
Answer: E