Question: In a forest, there are three anthills. In the first anthill, there are 100 ants, and in each next anthill, there are 20% fewer ants than in the previous one. How many ants are in the third anthill? Think carefully first, then make a decision:
In the second anthill, there are 20 / 100 * 100 = 20 ants less. This means there are 100 - 20 = 80 ants in the second anthill. In the third anthill, there are 20 / 100 * 80 = 16 ants less compared to the second one. So in the third anthill, there are 80 - 16 = 64 ants. So the answer is 64.