All right, so the first step would be to find the area of both the center and the whole.
The formula for area of a circle would be

The radius of the whole would be 17.5 in, and the radius of the center would be 3.5 in. Let's plug them in.
Whole:


Center:


To find the percentage, you would just have to find the fraction and turn it into a percent.

That's 4/100, so it would be
4%.