cone problem

At Cedar Point, Luke buys a cone full of Italian ice. He gets on the Top Thrill Dragster without realizing that there is a slight hole in the bottom of the cone. Luke sits down on the seat with his cone and the ice flows down onto his open dinner box. Given that the height of the cone is 10 cm, the radius of the base of the cone is 5 cm, the width of the box is 12 cm, the height of the box is 6 cm, and the length of the box is 4 cm. a) Find the volume of the cone b) Find the h' at which the V' is decreasing at 50 cm/second at height 8 cm..