The average weight of 8 men is increased by 2 kg when one of them, whose weight is 90 kg, is replaced by another man. What is the weight of the new man?

106 kg

Let average weight of 8 men is x

Total sum of weight = 8x

New average = x + 2

Sum of new weights = 8(x + 2)

90 kg is replaced by other, let it be y

so, 8x - 90 + y = 8(x + 2)

       y = 106 kg