well, so suppose those 2 quarters of a circle are from the whole circle of radius 10. Then The area of that circle would be pi*r^2= pi*10^2=100pi.
Half of that would be 50pi, so the area of the white regions is 50pi.
I got that from the fact that two quarters of a circle make a semicircle. So now, subtract 50pi from the area of the rectangle which is:
(10+10)*10=20*10=200