here we go...step by step
slope formula : (y2 - y1) / (x2 - x1)
now lets label ur points..
set 1 : (-2,8)...so we will call these : x1 = -2 and y1 = 8
set 2 : (5,3)..so we will call these : x2 = 5 and y2 = 3
now we sub into the formula...be sure and pay attention to ur signs...
slope = (y2 - y1) / (x2 - x1)
slope = (3 - 8) / (5 - (-2)
slope = -5 / (5 + 2)
slope = -5 / 7 <=== ur slope