Some birds were flying and met a bird on their way. The bird greeted them; hello hundred! They said we are not hundred, we need half of us plus you to make us hundred.

Question: How many birds were flying?

I'm not certain but it sounds as though there would be 150 birds flying.

Step-by-step explanation:

The first bird says we are not hundred, they need half their group population plus the second birds group population. So if we are trying to get 100 from two groups the easiest numbers would be to add 50 and 50. So if we have the second groups whole population be 50 birds then the first group's whole population must be 100. The first bird said half of us so that means half of 100 which would be 50. If you add half of the first groups population, which is 50 (100/2=50), plus the second groups whole population (50), you get 100 birds. Which means if you add the first groups total population (100) with the second groups total population (50) you get 150 total birds flying.