Read the problem carefully. This problem deals with sectors, which are sections of a circle. If you think of a circle as a pie, then sectors are slices of that pie.
Identify the bottom line. degrees in 1/6 of a circle - degrees in 1/9 of circle = ?
Assess your options. If a sector makes up 1/6 a circle, then that sector must contain 1/6 of the 360 degrees in the circle. Use that logic to figure out how many degrees are contained in each sector mentioned in the problem, then subtract the smaller number of degrees from the larger number to find the difference.
Attack the problem.
Loop back. Verify that you solved for the bottom line.
The correct answer is C.
This is a medium level problem.