To find the amount of flags we can make with this cloth, since we have the area of each small flag, we can calculate the total area of the cloth and divide by the area of each flag to see how many flags are contained in the area of the cloth.
The cloth has a triangular shape. The area of a triangle is given by half the product between the base of the triangle and the height.
Using this formula, the area of our cloth is

The cloth has 230 in².
Then, dividing the area of the cloth by the area of the small flag

Devin can make 2.875 flags. If we don't consider the fraction, Devin can only make two "full" flags with this cloth.