The points A and B have coordinates (3, 4) and (7, 6) respectively. The straight line l passes through A and is perpendicular to AB. Find an equation for l, giving your answer in the form ax + by + c = 0, where a, b and c are integers.
For the line passing through A and B: m = (y2-y1)/(x2-x1) = (-6-4)/(7-3) = -5/2
For the perpendicular line: m = -1/(-5/2) = 2/5
y - y1 = m*(x - x1) >> y - 4 = (2/5)*(x - 3) >> 5y - 20 = 2x - 6 >> 2x - 5y + 14 = 0
