Complex country & currency calculator needed for website

We need a payroll calculator built for working out potential payroll and employer hiring costs.

A competitor example to give you an idea of how it, in basic terms, needs to work: https://www.omnipresent.com/global-employment-cost-calculator.
I have also attached a code file as .txt (all it would let me upload) I have managed to scrape together of how I think this one is working.

Other websites with calculators of similar functionality/outputs:
– https://www.letsdeel.com/employee-cost-calculator (but form wouldn't be 'conversational' or require a job title)
– https://www.papayaglobal.com/cost-calculator/

The results need to load on the same page (ajax?!) but be bookmarkable so that someone can send the link to a colleague.

I have attached what we will provide for each country by our data researcher. There will be 43 countries to start with but should be each provided with the relevant formulas.

We have our own in house designers and front-end developers so we're only looking for the basic functionality that can then be styled by us. However, if you are able to offer the front-end build too, please quote!

It is to sit within a WordPress website so it is preferable it's written in either/both PHP and JS with an HTML output.

The project isn't due to start for 2-4 weeks but we want to make sure we find the right person to work with on this.

Please let me know if you have any questions.