so let's recall that a full circle has a total of 360°, and we also know that these two arcs are on 3 : 1 ratio.
Now, let's notice the points A and E, the line AE passes through the center of the circle, that means the arc made by ABCE is half the circle or 180°.
So if we just divide 180 by (3 + 1) and then distribute accordingly to each arc, we'll see how many degrees each arc really has

Check the picture below.