could you tell me how to figure out the positive and negative and grad? show the explain and steps. thank you so much

A contour diagram for the smooth function z = f(x, y) is in the figure above. (a) Is z an increasing or decreasing function of x? decreasing v Of y? increasing (b) Is fx positive or negative? negative v How about fy? positive > (c) Is fox positive or negative? positive v How about fyy? positive > (e) Is grad f longer at P or at Q? at P V