gallery price calculator

custom.js

'use strict'

const artistsPrice = document.getElementById('price')
const galleryPercentage = document.getElementById('percent')
const galleryCommission = document.getElementById('commission')
const galleryTotal = document.getElementById('total')
const btn = document.getElementById('calc')

function commissionCalc(price, percent) {
  const total = price * (1 + ( percent / (1 - percent / 100) / 100))
  return total
}

btn.addEventListener('click', () => {
  const galleryPrice = commissionCalc(artistsPrice.value, galleryPercentage.value)
  const commission = Math.round((galleryPrice - artistsPrice.value) * 100) / 100
  galleryCommission.innerHTML = commission.toFixed(2)
  galleryTotal.innerHTML = galleryPrice.toFixed(2)
})

index.html

<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <title>JavaScript Gallery Price Calculator</title>
  <meta name="robots" content="noindex, nofollow">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="styles.css">
</head>

<body>
  <header>
    <h1>JavaScript Gallery Price Calculator</h1>
  </header>
  <div class="wrapper">
    <div class="container">
      <p>Formula: x * (1 + ( y / (1 - y / 100) / 100)), where x is the artists price and y is the gallery percentage.</p>
      <div id="calculator">
        <table>
          <tr>
            <td>Artists Price: $</td>
            <td>
              <input id="price" type="text">
            </td>
          </tr>
          <tr>
            <td>Gallery Commission: %</td>
            <td>
              <input id="percent" type="text">
            </td>
          </tr>
          <tr>
            <td>Gallery Commission: $</td>
            <td id="commission"></td>
          </tr>
          <tr>
            <td>Gallery Total: $</td>
            <td id="total"></td>
          </tr>
        </table>
        <button id="calc">Calculate</button>
      </div>
    </div>
    <!-- .container-->
  </div>
  <!-- .wrapper-->
  <footer>
    <small><a href="https://opensource.org/licenses/MIT">MIT</a></small>
  </footer>
  <script src="custom.js"></script>
</body>

</html>

styles.css

body {
  background: #eeeeee;
  font-size: 16px;
  font-family: "Trebuchet MS", Helvetica, sans-serif;
  margin: 0;
}

a {
  color: crimson;
  text-decoration: none;
}

a:hover {
  color: red;
}


/* Layout
------------------------------------------*/

header,
.container,
footer {
  margin: 0 auto;
  width: 88%;
  max-width: 1080px;
}

.wrapper {
  padding: 1em 0;
  background: #ffffff;
}


/* Table
------------------------------------------*/

td:first-child {
  text-align: right;
}

td {
  padding: .5em 0 .5em .7em;
}

tr:last-child td:last-child {
  border-top: 2px solid black;
}

#calculator {
  max-width: 376px;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
}

input {
  font-size: 1em;
  background: linear-gradient(#eeeeee, #ffffff);
  border-top: 2px solid #cccccc;
  border-left: 2px solid #cccccc;
  border-bottom: 2px solid #eeeeee;
  border-bottom: 2px solid #eeeeee;
  padding: .5em;
}

button {
  font-size: 1em;
  border: none;
  background: linear-gradient(#ffffff, #eeeeee);
  outline: 0;
  padding: .5em 1em;
  border-radius: 15px;
  text-shadow: 1px 1px 3px rgba(198, 198, 198, 0.9);
  border: 2px solid #eeeeee;
}

button:hover {
  background: linear-gradient(#eeeeee, #ffffff);
}