Solution 1: Treat all 30 rabbits,
(30*4-78)/2
=( 120-78)/2
=42/2
=2 1 (only)
30-2 1=9 (only)
Answer: 2 chickens1and 9 rabbits.
Solution 2: Treat all 30 rabbits,
(78-30*2)/2
=(78-60)/2
= 18/2
=9 (only)
30-9=2 1 (only)
2. The chicken and the rabbit are in the same cage. * * * has 20 heads and 56 feet. How many chickens and rabbits are there?
Chicken: (20*4-56)/2
=(80-56)/2
=24/2
= 12 (only)
Rabbit: 20- 12=8 (only)
3, chickens and rabbits in the same cage, * * * has a head 43, feet 132, how many chickens and rabbits are there?
Chicken: (43*4- 132)/2
=( 172- 132)/2
=40/2
=20 (only)
Rabbit: 43-20=23 (only)