According to the meaning of the question, you can draw the following picture. The big rectangle is the original iron sheet, the gray part is cut off and the white part is left. At this time, the area of the iron sheet can be calculated.

After cutting, as shown below.

Fold the box as shown below along the dotted line, and then you can calculate the volume of the iron box. (Note: It's not good without a cover painting, I have a cover painting.)

explain

Solution: 30×25-5×5×4=750- 100=650 (square centimeter)

(30-5× 2 )× (25-5× 2 )× 5 = 20×15× 5 =1500 (cubic centimeter)

A: This box is made of 650 square centimeters of iron, and its volume is 1500 cubic centimeters.

Considering my efforts in drawing and typing ~