The slope of y = -x is m = -1. Thus, starting with the slope-intercept form y = mx + b, we substitute -1 for m, 8 for x and 2 for y, to determine the vaue of b:
2 = -1(8) + b, or 10 = b. Then the equation of the line parallel to y = -x and passing thru (8,2) is:
y = -x + 10.
