Question 88619
slope of any line  through points (6, 3) and (7, 7) = (7-3)/(7-6)
                                                    = 4/1
                                                    = 4

So slope of any line perpendicular to the line 
through points (6, 3) and (7, 7) = -1/4 [as the product of slopes of perpendicular lines is -1]

The answer is -1/4