Question 1023773
eq 1. xy = -8000
eq 2. x+y = 20

from eq 2. y = 20 - x
substituting y to eq. 2

x(20-x) = -8000

20x - x^2 = -8000, rearraging to ax^2 + bx + c = 0

x^2 - 20x - 8000 = 0; a = 1; b = -20; c = -8000

using quadratic formula
x = 100 and -80