if x.y=30 and x+y=10.3, what is x?

i been told by my teacher to use quadratic formula , and him and i did it , we end up having , x1=-5.15-5.89i and x2=-5.15+5.89i, y1=30/(-5.15-5.89i) and y2=30/(-5.15+5.89i).and he told to go from there, but i cant get final answe. as you know i=square root of -1. but i can solve this
(-5.15-5.89i)times 30/(-5.15-5.89i) ???

xy=30 and x+y = 10.3

that means y = 10.3-x from equation two now put that into equation one

x(10.3-x)=30
x2-10.3x+30 do the quadratic thing now