It is known that the corresponding point of ant A is 3, the speed per second is 3 units, the corresponding point of ant B is -2, the speed per second is 4 units, there are 3 grains of food at point C, and each ant can only move one grain. When the corresponding point of C is 9, what is the fastest time for two ants to move food to 0?

Solution:

The time for ant B to move food to 0: [(9+2)+9]÷4=5 (seconds).

The time for ant A to move food to 0: [(9-3)+9]÷3=5 (seconds).

∫ The speed of ant A