There are three arts of chameleon: red, blue, yellow. One morning there are 20 blue, 30 yellow, 50 red. In the evening 100 red. Is it possible?
If two different meet, they become the third color. If two similar, they become the second and third color.
From the information given in the question there are originally 50 red, 30 yellow and 20 blue creatures. Also we know that if two creatures of different color meet, both change to the 3rd color and if two creatures of the same color meet half of them change to the second color and half to the third.
So let's start:
Initially there were 50 red creatures.
Now let 20 of the blue and 20 of the yellow creatures meet, all 40 change to red.
So now we have 90 red and 10 yellow.
Now let the ten meet each other, 5 turn to red and 5 turn to blue.
Now let 4 of the yellow meet each other, 2 change to red and two to blue.
So we have 1 yellow, 2 blue and the rest red.
Now when the two blue meet, we have 1 red and 1 yellow.
Finally the two yellow meet, 1 turns red and the other blue.
Therefore finally there are 99 red and 1 which can either be blue or yellow depending on how you go about it.
It is not possible to get all red finally.