Related Rates - Area & Volume

Ok I have done this problem several times over and my computer is telling me that all of my answers are wrong . Please help!

We assume that an oil spill is being cleaned up by deploying bacteria that consume the oil at https://webwork.math.ohio-state.edu/...e94e38c1d1.png cubic feet per hour. The oil spill itself is modeled in the form of a very thin cylinder as depicted below. Its height https://webwork.math.ohio-state.edu/...11a2eaba01.png is the thickness of the oil slick. Suppose at some moment in time the height is decreasing at https://webwork.math.ohio-state.edu/...e34fcdddc1.png foot per hour, the thickness of the slick is https://webwork.math.ohio-state.edu/...e9ca699bc1.png foot, and the cylinder is https://webwork.math.ohio-state.edu/...21638a64b1.png feet in diameter. At what rate is the area covered by the slick changing at that moment? (That is, the area of the base disc of the cylinder).

I have been finding dr/dt by taking the derivative wrt time of v+pir^2*h and then using dr/dt to find dA/dt by deriving A=pi*r^2. Please Help!