AB has a slope of y2 - y1 / x2 - x1 so -8-5/3-3 so -13/0 = undefined so it is a vertical line, so any line that is horizontal will be perpendicular to it, so horizontal lines have a zero slope
Well in order to find how many toy cars were in each package you would need to divide the number of toy cars by the number of packages. So your expression would be p / 6.