JSFiddle - React, Tailwind, and code Playground

HTML

<div id="result"></div>

CSS

body{font-size:12pt;}
#result{width:300px;height:300px;background-color:#afa;}
#result p{color:#f44;font-weight:600;}

JavaScript

var hoursworked = window.prompt("How many hours worked?", ""),
    payrate = window.prompt("What is the pay rate?", ""),
    payrate = parseFloat(payrate).toFixed(2),
    taxrate = window.prompt("What is the tax rate?", ""),
    taxrate = parseFloat(taxrate).toFixed(2),
    netpay = 0;

function calculatepay() {
    var grosspay = hoursworked * payrate,
        taxamount = (grosspay * taxrate) / 100,
        netpay = grosspay - taxamount;
    return netpay;
}

var result = "<p>Hours Worked: " + hoursworked + "</p>" 
    + "<p>Hourly payrate: " + payrate + "</p>"
    + "<p>Tax rate applied: " + taxrate + "</p>"
    + "<p>Net Pay = " + calculatepay() + "</p>";

document.getElementById('result').innerHTML=result;