Answer
$$ - 3i$$
Work Step by Step
$$\eqalign{
& {\text{Let }}{\bf{u}} = 5 - 6i,{\text{ and }}{\bf{v}} = \, - 5 + 3i \cr
& {\text{Find the sum }}{\bf{u}} + {\bf{v}} \cr
& {\bf{w}} = {\bf{u}} + {\bf{v}} \cr
& {\bf{w}} = \left( {5 - 6i} \right) + \left( { - 5 + 3i} \right) \cr
& {\bf{w}} = 5 - 6i - 5 + 3i \cr
& {\text{Add real parts}},{\text{ and add imaginary parts}} \cr
& {\bf{w}} = - 3i \cr
& \cr
& {\text{Graph}} \cr} $$
