Explanation:
The circle as a whole is one.
So to find the shaded area find a common denominators for both first
1/4 = 7/28
2/7= 8/28
Add the two together
7/28 + 8/28 = 15/28
This is the area taken up the the white fractions areas
Now because the circle is one
28/28 - 15/28 = 13/28
So the area of the blue is
13/28
Hope this helped :)