What is the equation of the line containing the given pair of points.

(1,3) (3,4)

easiest way:

slope = (4-3)/3-1) = 1/2

so the equation is x - 2y = c
but (1,3) lies on it, so
1 - 6 = c = -5

x - 2y = -5

This method is based on the fact that for
Ax + By = C, the slope is -A/B