Question

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, then the weight of B is

Answer 1

let d sum of a, b, c is 3*45=135
and sum of a and b s 2*40=80
sum of b and c is 3 *43=86
hence 80+86-135=31
ans=31

Answer 2

a+b+c/3 =45
a+b+c=45×3=135---------1
a+b/2 =40
a+b=80------------------2
b+c/2=43
b+c=86-------------------3
add 3nd 2
a+b+b +c =166
135+b =166
b=31