5. (30%) Find the volume of the described solid. (a) The solid is under the surface z = xy + yz and above the triangle in the ry-plane with vertices (0, 0), (2, 2), and (0, 4). (b) The solid in the first octant is above the plane z = 2 and below the paraboloid z = 9 - x2 -y2. (c) The solid is above the cone z = vx2 + y? and lies between the spheres x2 + y2 + z2 = 1 and x2 +y2+ 22 = 16