Let f be the function defined on (0,3] > [0,3] whose level curves are given above. (a) Approximate the value of f(1, 1.5). (b) Approximate the value of f(1, 2.5). (c) If we start at the point (1, 1.5) and move to the point (1.5, 1.5), is the function increasing or decreasing? At approximately what rate?