As the weather gets colder and colder, the grass on the pasture is not growing, but decreasing at a fixed rate. As we all know, a piece of grass on the grass can feed 20 cows for 5 days.

Suppose 1 cow eats 1 serving of grass every day.

20 cows ate 20×5= 100 portions of grass in 5 days.

12 cows ate * * 7 days: 12×7=84 portions of grass.

Time difference: 7-5=2 (days)

Grass quantity reduction: 100-84= 16 grass.

Description, single-day reduction: 16÷2=8 servings of grass.

5 days less: 8×5=40 grass.

Originally, there were: 100+40= 140 grass on the pasture.

140 portions of grass can feed six cows: 140÷(6+8)= 10 (day).