Analysis:

1. If each monkey eats five, there are seven left, which means there are seven apples left to eat.

If each monkey eats seven, five are missing, that is, there are five apples left to eat.

From these two conditions, we can know that the difference between eating apples twice is 7+5= 12, that is, the second time is more than the first time 12.

The first time a monkey ate five, the second time each monkey ate seven, and the second time each monkey ate more than the first time: 7-5=2.

Then, if a monkey eats two more, it needs six monkeys to eat more 12. 12÷2=6 (only)