What can multiply to give you 80 but add up to give you 11

There are no real numbers that can do that job.

There's a pair of complex numbers that can do it.
They are

         5.5 + i4.97
and
         5.5 - i4.97 .

     ' i ' = the imaginary unit = √(-1)

Answers4.) -1/205.) -1/406.) -55/127.) -3/4