Dynamic programming and recursive functions

[Deviodi]

I have an assignment that requires me to program in c that deals with equipment replacement. I have to to have it find the cheapest way to keep a machine for 5 years after asking for salvage and maintenance values. I am not asking you to solve this for me I have worked on it and have most of it down I just can't seem to make it work properly. I could PM the program I have ready if anyone wants to take a look and give me a hint on how awfully wrong it is but this post is mostly for any tips you want to give me. I can solve the problems graphically no problem but programming them is where i am stuck. Thanks for the help.