You can count the number of triangles of each color, and use Heron's formula to compute the area of one triangle.
I notice that the umbrella has an angle deficit of almost $130°$. So disregarding the elasticity of the cloth, it would form a cone where opposite lines at the apex form an angle of less than $80°$, unless I made a mistake in my calculation. I would feel somewhat uncomfortable under such a high but narrow umbrella! But none of this is required to answer the question, just shows that the numbers probably didn't come out of actual umbrella production. Or it was umbrellas for little kids.