Let h be the number of hats and s be the number of scarves that Alex can bring to the art fair. Then, the system of inequalities can be written as:
h ≤ 20 (since he can make at most 20 hats)
s ≤ 30 (since he can make at most 30 scarves)
h + s ≤ 40 (since he can make no more than 40 items altogether)
h + s ≥ 25 (since he wants to bring at least 25 items)
To graph this system of inequalities, we can plot the lines h = 20, s = 30, h + s = 40, and h + s = 25, and shade the region that satisfies all the inequalities. The resulting graph will be a quadrilateral with vertices at (20, 0), (0, 30), (10, 15), and (20, 5). The shaded region will be the area inside this quadrilateral that is above the line h + s = 25.