Question 1090477
If it is something like this (or its mirror image,
with A on the left end)
{{{drawing(300,300,-1.01,1.05,-1.1,1,
arrow(0,0,-1,0),arrow(0,0,1,0),
arrow(0,0,-0.669,0.743),arrow(0,0,0.407,0.914),
circle(-0.8,0,0.02),circle(0.8,0,0.02),circle(0,0,0.02),
circle(-0.535,0.595,0.02),circle(0.325,0.731,0.02),
locate(-0.82,-0.02,B),locate(-0.02,-0.02,O),locate(0.78,-0.02,A),
locate(-0.58,0.6,C),locate(0.35,0.76,D)
)}}}
The phrase "12 less than..." tells me that it is {{{12^o}}} ,
and that angles are supposed to be measured in degrees
Let it be {{{x=BOC}}} .
Then, {{{AOC=3x-12}}} , and
{{{AOC+BOC=AOB}}}
translates into {{{AOC+x=180}}} and
{{{3x-12+x=180}}}
Simplifying and solving:
{{{4x-12=180}}}
{{{4x=180+12}}}
{{{4x=192}}}
{{{x=192/4}}}
{{{x=48}}}
{{{AOC=180-48=132}}} 
Then {{{AOD=COD=AOC/2=132/2=highlight(66)}}}