What conversion factors should be used to convert from gigameters to liters

Which value of m will create a system of parallel lines with no solution? y = mx - 6 8x - 4y = 12

Which statement explains how you could use coordinate geometry to prove the opposite sides of a quadrilateral are congruent? a. use the slope formula to prove the slopes of the opposite sides are the same. b. use the slope formula to prove the slopes of the opposite sides are opposite reciprocals. c. use the distance formula to prove the lengths of the opposite sides are the same. d. use the distance formula to prove the midpoints of the opposite sides are the same.

Can someone me with this? i’m not sure what to put for my equations.