The solution is 73°. According to one of the circle theorems, the angle formed by the intersecting chords is equal to the average of the arcs intercepted by the angle and its vertical angle.
[tex]\frac{170 + 44}{2}[/tex] = 107°
So m∠DOC = 107°
Since m∠DOB is supplementary to m∠>DOC we know that its measure is 73°.
