Meteorology pasture

Solution 1:

Let the daily grazing amount of cattle be X and the natural decrease amount of grass be T, then it is10 (40x+t) =12 (30x+t), from which t=20x can be obtained.

That is, the total amount of grass is 600x X x.

If you eat for 20 days now, the grass will be reduced by 600x/20=30x, 30x-t= 10x, so it is 10 cattle.

Solution 2:

In fact, it is the explanation of the above solution ..

The amount of grass eaten by 40 cows 10 day is actually equivalent to the amount of grass eaten by 400 cows in Niu Yi and the amount of grass naturally reduced by 10 day.

The amount of grass eaten by 30 cows 12 day is actually equivalent to the amount of grass eaten by 360 cows in Niu Yi and the amount of grass naturally reduced by 12 day.

As the two are equal, it can be seen that the amount of grass eaten by the first 40 Niu Yi cows is equivalent to the amount of grass naturally reduced in the pasture within two days, so the reduced amount of grass in one day can feed 20 Niu Yi cows for one day. Visible pasture grass can feed 600 Niu Yi days.

Now it takes 20 days to eat, and the total amount of grass naturally reduced in the pasture is equivalent to 20×20=400 Niu Yi days, so only 200 cows can eat together. An average of 20 days is 10 cattle/day.

Is this ok?