After a 40DM high cylinder steel is cut into two cylinders, the surface area increases by 25.12 square decimeters. What is the volume of the original cylinder

After a 40DM high cylinder steel is cut into two cylinders, the surface area increases by 25.12 square decimeters. What is the volume of the original cylinder

25.12 / 2 * 40 = 502.4 (cubic decimeter)
A: the original volume of the cylinder is 502.4 cubic decimeters