Question

Find an equation of the line that passes through the points (1,6)&(2,4).

Answer 1

The two-point form makes use of the fact that the slope of the line is constant. In particular, the slope between (1,6) and (x,y) is the same as the slope between the two points:

(y-6)/(x-1) = (4-6)/(2-1)

now massage that into whatever form you wish.