The size of the reflex angle in the image is 80 degrees.
The image shows a reflex angle, which is an angle that measures more than 180 degrees but less than 360 degrees.
To find the size of the reflex angle, we can subtract 360 degrees from the angle's total measure.
The angle in the image is made up of two smaller angles: a 180 degree angle and a 100 degree angle. The total measure of the angle is therefore 180 degrees + 100 degrees = 280 degrees.
Since the angle measures 280 degrees, it is a straight angle.
So the reflex angle in the image has a measure of
360 degrees - 280 degrees = 80 degrees.