Puzzle

Can you figure out how the p and q sliders control the lines? To check your answer, try typing in equations of the lines (in terms of p and q) in the blank rows underneath the sliders and see if the lines that your equations produce match the lines that are already there. (When you've found something that works--but not before, that's cheating!--you can scroll down to rows below the blank ones to see if your equations are the same as the ones that were actually used to produce the lines.)