A line contains the points (3,8) and (4,13). Find three more points that lie on the line.

(I want to solve this without a graphing calculator)

I know the answer is (a), but how do you figure it out?

a) (2,3), (5,8), (6,23)

b) (2,3), (5,23), (6,18)

c) (-2,-3), (-5,-18), (-6,-23)

d) (2,23), (5,18), (6,3)