line through points P(-3, -2) and Q(2, 3)
slope = (3 + 2)/(2 + 3) = 5/5 = 1
line through points R(10, -1) and S(15, -6)
slope = (-6 + 1)/(15 - 10) = -5/5 = -1
perpendicular lines, slope is opposite and reciprocals
slope of line PQ = 1 and slope of line RS = -1
So they are perpendicular
answer
c. Yes; their slopes have product -1.