Question 903771
Remember that in complex numbers, i^2 = -1 
We will use FOIL to solve this problem.

(-6 - 5i )(1+ 3i)
= -6 -18i - 5i -15i^2
= -6 - 23i - 15i^2
= -6 - 23i -15 (-1)
= -6 - 23i + 15
=  9-23i