Coldworking materials Mathematics help please

[Guest CarreraGT]

Hey guys Im pretty much stuck on this problem and really need some help it may seem easy to most of you but I am finding it difficult

Here is the question....

 

c) An annealed 50mm x 50mm square cross section 30%Zn/Cu brass bar is drawn by several cold working steps to a final Square cross section of 20mm x 20mm. The final cold worked bar must have

Tensile strength grater than 360mpa

Yield stength greater that 300mpa

And Elongation (ductility) Greater than 15%

 

Refer to Diagram below

 

Describe the steps involved including the % cold work in each step & intermediate thicknesses required if a maximim of 70% cold work is allowed at each work step.

 

 

If anyone could help that would be much appreciated thank you.