Simplyfy (-3-9i)/(5-8i)

To simplify something like that, you just multiply numerator and denominator by conjugate of denominator.

Our denominator is 5-8i, so our conjugate of denominator would be 5+8i.

[ (-3-9i)(5+8i) ] / [ (5-8i)(5+8i) ]

Now we can simplify from here;

[ -15 - 45i - 24i - 72i^2 ] / [ 25 - 64i^2 ]

[ -15 - 45i - 24i + 72 ] / [ 25 + 64 ]

[  57 - 69i  ] / [ 89 ]

 (57 - 69i) / 89

Hope this helps.