Again the problem can't be answered with just the information shown in the diagram. We know the diameter of the largest circle is 20, so the sum of the diameters of the two smaller circles is 20. But we are not told that the two smaller circles are the same size.
So to solve the problem we have to make an assumption; it is likely that the two smaller circles are supposed to be the same size.
So the diameters of the two smaller circles are each 10.
Then the area of the shaded region is the area of the large circle with radius 10, minus the area of two circles each with radius 5:
