If quantity is input then info moves into other worksheet

Hi

I am hoping that you can help. I have a file with 3 worksheets. Two worksheets #400 and #600 are for customers that will input in quantity how many printers or frames that want to order. If they input quanity in either #400 or #600 sheet then I would like to have this show up in the sheet called final results.

Can this be done and how? I am an OK Excel but no expert by any means.

Thank you very, very much in advance.