the correct question is
Ray bd is the angle bisector of angle abc. m∠abc is 168° what is the measure of ∠dbc?
we know that
if bd is the angle bisector of angle abc
then
m∠abd= m∠dbc
and
m∠abd=(1/2) m ∠ abc
m∠abd=(1/2)*(168°)-------> m∠abd=84°
therefore
m∠dbc=84°
see the picture attached to better understand the problem