Question

A rectangular tube is being made. The outside of the tube is 15 cm long, 6 cm tall and 10 cm wide. The hollow core is in the middle and runs the length of the tube. How much metal is needed to make this tude?

Answer 1

tube wall thickness?

Answer 2

the volume of metal is just the cross-section area times the length.
If the walls have thickness x then the cross-section area of the metal is just

6*10 - (6-2x)(10-2x)