Lines AB and CD intersect at a point O in such a way that ∠DOB = 5∠COB. What is ∠AOD?
A C
O
D B
DOB and COB are supplemental
So
5COB + COB = 180
6COB = 180
COB = 30
And AOD is a vertical angle to COB so it also = 30 (degrees)
