Geometry
posted by Sheila .
ray OB is the bisector of angle AOC and ray OC is the bisector of angle BOD. m<AOD =120 find m<AOB

Since OB bisects AOC, AOB=BOC
Since OC bisects BOD, BOC=COD
So, all 3 angles are equal, and are 120/3 = 40
yeah, I know, the terminology is loose, but you can fill in the appropriate correct language