how do you identify which lines are parallel?
ex. x=7;y=-5/6x+8;y=-5/6x-4;x=-9

Parallel lines have the same gradient. Does that help you at all? I can't say much more without giving it away :)

You should know how to identify the gradient from what you have been taught in class.

parallel lines have the same gradient.

In the US we call it "slope." Parallel lines have the same slope. The general form of a line is y = mx+b, where m is the slope and b is the y-intercept point. You should be able to do these problems now.