Here we're finding the equation of a 'new' line which passes thru (1,3) and is parallel to the orange line. We need the slope of the orange line, which will also be the slope of the new line thru J.
-2 - 1 -3
m = --------- = ------ = -1/2
2-(-4) 6
Then the equation of the new line, in point-slope form, is
y - 3 = (-1/2)(x - 1).