Chickens and rabbits have 5 heads and 17 legs in the same cage. How many chickens and rabbits are there? Suppose all chickens, 17-5*2=7 7÷2=35.

5*2 have only 1 legs, and

17-5*2=7

actually have 7 extra legs. All the extra ones are rabbits'. 5*2 already includes two legs of each rabbit, so in 7 legs, each rabbit has two legs left, so dividing by 2 is the number of rabbits.

There is a joke on the Internet, which can explain this question:

Every chicken and rabbit should lift two legs, and one * * * lifts 1 legs, leaving 7 legs on the ground. The chicken has no legs on the ground, and each rabbit has two legs on the ground.