perpendiculare lines have slopes that multiply to -1
find slope
given (x1,y1) and (x2,y2) the slope would be (y2-y1)/(x2-x1)
so
given
(7,-11) and (8,17)
slope=(17-(-11))/(8-7)=(17+11)/1=28
28 times what=-1
divide by 24
what=-1/28
slope is -1/28
answer is B