(for every 5 down go 2 to right )

i.e. we decrease x by 2 and decrease y by 5

i.e. ( 1 + 2 = 3, 3 - 5 = -2 ) = (3, -2)

or (for every 5 up go 2 to left)

i.e. (1 -2 = -1, 3 + 5 = 8 ) = (-1, 8)

Hence the other two points on the line through (1, 3) are (3, -2) and (-1,8).