The area of the field is 36,000m², and in that area he can have 18 sheeps.
How many sheeps can he have in that field?
To find the area of the field, we can find the area of a square of 200m by 200m, and then subtract the area of a triangle of base of 100m and height of 80m.
The area of the square is:
S = 200m*200m = 40,000m²
The area of the triangle is:
T = 100m*80m/2 = 4,000m²
Then the area of the field is:
Area = 40,000m² - 4,000m² = 36,000m²
and each sheep needs 2,000m², then the number of sheeps that she can has is:
N = 36,000m²/2,000m² = 18