Find the slope of any line perpendicular to the line through points (6, 3) and (7, 7).

We know two points on the line, hence we can find its' gradient.

gradient = (difference of y co-ordinates)/(difference of x co-ordinates)

gradient =  =  = 3

This is the gradient of the line, 3.

A line which is perpendicular to our line we use the following formula:

gradient of line x gradient of perpendicular = -1

3 x gradient of perpendicular = -1

gradient of perpendicular =