As you should be.
The arrow appears to be pointing to a line segment, but it is labeled x°, suggesting an angle or arc measure.
Arcs DA + AB + BC add to the measure of a semicircle, 180°, so arc DA is
... DA = 180° - AB - BC = 180° - 130° - 40° = 10°
If you believe x is supposed to be the measure of arc DA, the appropriate choice is a. 10.
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The measure of angle M will be half the difference of arcs BC and AD:
... ∠M = (BC -AD)/2 = (40 -10)/2 = 15
If you believe x is supposed to be the measure of angle M, the appropriate choice is d. 15. (That's my personal choice, but a case can be made for x pointing to arc AD.)