Suppose that $f(x)$ is continuous on $-3,6$ and $f(x)<mn\; id="EditorElement\_180194">0</mn>$ on $-3,6.$ If the area between $f(x)$ and the $x-$axis on $-3,614,$ then find the average value of $f$ on this interval. $\frac{14}{9}\frac{14}{3}-\frac{14}{3}-\frac{14}{9}0-14$