(Applications of Differentiation and Partial Derivatives). Answer the following. URGENT!!!Thankyou!

An open box is to be made from a 16-inch by 3--inch piece of cardboard by cutting out squares of equal size from the four corners and bending up the sides. What size should the squares be to obtain a box with the largest volume? Find the radius (r) and height (h) of the right circular cylinder of largest volume that can be inscribed in a right circular cone with radius 6 inches and height 10 inches. (The formula for the volume of the inscribed cylinder is V = mr h) Determine fr(1, 2) for the function f(x, y) = 2x y + 3x + 4y. Determine fy(1, 2) for the function f(x, y) = 2x y + 3x + 4y