Answer:
60 degrees
Explanation:
The wheel is a circunference, so it has a total of 360 degrees. As we have 12 chairs evenly spaced, this 360 degrees will also be divided evenly, so the angle between each pair of chairs is equal to 360 / 12 = 30 degrees.
As we want the angle between chairs B and D, we have two spaces between chairs (the space between B and C and the space between C and D), so the angle is 2 * 30 = 60 degrees