(3,-7)(1,-3) slope

Slope is defined as  rise / run    or   (y2-y1) /(x2-x1)      It does not matter which point you label as (x1,y1)   or  (x2,y2) , just use the formula......for your chosen points:

(-3 -(-7)) / (1-3)   = slope = (-3+7) / (1-3) =  - 4/2 = -2