Solution: The daily grass length is (20 *10-24 * 6)/(10-6) = (200-144)/4 = 56/4 =14 (ox day).

Grassland grass quantity: 24 * 6-14 * 6 =144-84 = 60 (ox day).

Suppose: this pasture can feed 19 cows for x days.

Then: 60+ 14 * x = 19 * x, 5x = 60, x = 12 (days).

A: This pasture can feed 19 cows 12 days.