Line q is decreasing (negative slope), whereas line p is increasing (positive slope). Moreover, the absolute value of the slope of line q is higher that the one of line p, because line q is more "vertical" than line p.
Finally, line p passes through the origin (b=0), whereas line q has a y-intercept of 3 (constant term=3).
So, the most feasible expression for line q would be y=-2ax+b+3
