Convert/re-write working Excel VBA XLS file to a Web Based App (to calculate Tax)

Hello I have two Excel files which run macros and VBA code to calculate Tax. (see the attached zip file for the files with the code etc.) I would like to convert/copy/re-write these two programs into Web based Apps. Summary: I simply want to copy/replicate what these two Excel files do but in a web based App. I do not mind what language is used or what technology you wish to use in order to achieve what I need. I will take your advice on that and/or you can use what you prefer. I hope this is of interest? Thank you. I appreciate your replies, Bids, thoughts and advice. Best regards Greg