How Close to Perpendicular Can You Get? Open Middle Challenge

Creation of this resource was inspired by this Open Middle problem submitted by Shelli Foust and Robert Kaplinsky.

DIRECTIONS:

Using the digits 1-9 at most one time each fill in the coefficients of the three linear equations to the right so that any two lines are parallel and the third line is a transversal that passes through the other two. Note: There are several possibilities!

AS AN ADDED CHALLENGE:

Repeat the task above, yet this time try to get the transversal (not parallel to the other 2 lines) as "close to perpendicular" to the other two parallel lines as possible! How close to 90 degrees can you get the transversal to intersect the other 2 parallel lines?