There are 12 heads and 40 feet in the same cage. How many chickens and rabbits are there in the cage?
There are: (40-12 × 2) △ 4-2, = 16 △ 2, = 8 (rabbits); there are: 12-8 = 4 (chickens); a: there are 4 chickens and 8 rabbits
There are: (40-12 × 2) △ 4-2, = 16 △ 2, = 8 (rabbits); there are: 12-8 = 4 (chickens); a: there are 4 chickens and 8 rabbits