And180y

First time posting so hopefully it is okay to ask for some help. Sorry for the long post. Due to it being a long time since I did anything for the web (think Frontpage days lol) and needing to convert a load of Excel stuff to the web I found it necessary to use a form builder. One of the calculation fields needed more work on it so I (foolishly, it seems)ended up on Fiverr. The guy couldn't fix the coding so I ended up with a completely different form which still didn't calculate correctly and looked hideous. Most of the issues in that form seemed to be down to the functions. (I thought if I could get them working I could figure out the design) but when I ran them through a Javascript checker it seemed a nightmare. So I built another form but am back to my lack of knowledge in functions. I reckon if someone pointed me in the right direction I could get there, would anyone be willing to have a look please?