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?
Choose the correct choice.
A) 28	B) 30	C) 32	D) 34	E) 31
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)   =&gt; a + b + b + c - (a + b + c) = 80 + 86 - 135   =&gt; b = 80 + 86 -135 = 166 - 135= 
<gadget id="calculator">166 - 135</gadget>
<output>31</output>
31   Weight of B= 31 Kg   Answer is 31.
<result>E</result>
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?