Which pair of slopes could represent parallel lines?

m = 7; m = 49

m = 2/7; m = 7/2

m = - 3, m = - 9/3

m = - 1/2, m = - 2

M = - 3, m = - 9/3

because when you divide - 9/3, you get - 3, so the slopes would be the same.

If the slopes are the same (and their intercepts are different) then that pair of slopes represents parallel lines!