Steps to solving:
1) Rearrange!
5+(-8)+(-5i)+(-6i)-(2+3i)
2) Distribute!
5+(-8)+(-5i)+(-6i)+2+(-3i)
3) Rearrange again!
5+2+(-8)+(-3i)+(-5i)+(-6i)
4) Simplify! [Let's do "i" first]
-3i+(-5i)+(-6i)= -14i
5+2+(-8)+(-14i)
5) Simplify! [Now do the constants]
5+2= 7+(-8)= -1
6) Refine!
-14i+(-1)