answer and clarify ecah step with diagrams use application of derivatives in the questions to solve

__-_J-.__ 12. The area of a given rectangular plate is a given value A, but its dimensions are not given. One may make a cuboid without a side out of this plate by cutting four equal squares from the four corners of the plate, and bending the four resulting edges. For what dimensions of the plate one would obtain the maximum volume of the cuboid? What is the value of this maximum