A special CD is manufactured and its manufacturing costs is given by the equation C(x) = 0.08x^2 + 0.2x + 3200. If the price function is given by the equation p(x) = 33 - 0.02x, determine the price that should be charged

a) to maximize profits

Now I don't know what to do. . .? I can't seem to find the zeros of the first derivative. . .