Final answer:
b. 80. Hamid's normal weight is 80 kg.
Step-by-step explanation:
To find Hamid's normal weight, we need to reverse the 10% increase in weight. Let's call his normal weight N. Since his weight is now 10% higher, it can be calculated as N + 0.1N = 1.1N. We know that 1.1N is equal to 88 kg, so we can set up the equation 1.1N = 88 and solve for N by dividing both sides of the equation by 1.1. Therefore, N = 80 kg.