There are 20 chickens and rabbits in Happy Farm. They are 48 feet. There are (4) rabbits and (16) chickens on the farm.

Rabbit (48-20x2)÷2=4.

Chicken 20-4= 16

4: 40 =(4 2/3)

3.7 liters = (3,700) ml.

The number of school chorus is between 50 and 60, and the ratio of male to female is 4: 7. There are (55) people in this choir.

Make this number proportional to 2, 0.8, 1/4. 2: 0.8 = 1/4: 1/ 10.