pris.html

<script>
  function value(sell, improvements) {
    let value = sell;
    let currentLoan = 500000 + 692000 + 790000 + 772000;
    let trust = 41220;
    let stamp = 58500;
    let dealer = Math.min(sell, 4300000) * 0.022 + Math.max(sell - 4300000, 0) * 0.1;
    let cash = 0.3 * 3900000;

    let profit = sell - 3900000 - dealer - (4100000 * 0.7 - 1600000) * 0.015 - improvements;

    let tax = Math.max(profit, 0) * (22/30) * 0.3;

    value -= currentLoan + trust + stamp + dealer + cash + tax;

    return {value, profit, tax};
  }

  function update() {
    let data = +document.getElementById('input').value;
    let improvements = +document.getElementById('improvements').value;
    let estimates = value(data, improvements);
    document.getElementById('output').innerText = Math.round(estimates.value);
    document.getElementById('output-profit').innerText = Math.round(estimates.profit);
    document.getElementById('output-tax').innerText = Math.round(estimates.tax);
  }

  function init() {
    update({value})
  }

  addEventListener('load', init)
</script>
<style>
 .result {
     text-align: right;
 }
</style>

<br />
<table>
  <tr>
    <td>
      Improvement costs:
    </td>
    <td class="result">
      <input id="improvements" type="number" value="70000" onchange="update()" onclick="update()" step="1000">
    </td>
  </tr>
  <tr>
    <td>
      Sell for:
    </td>
    <td class="result">
      <input id ="input" type="number" value="4200000" onchange="update()" onclick="update()" step="10000">
    </td>
  </tr>
  <tr>
    <td colspan="2">
      <input type="button" value="Update">
    </td>
  </tr>
</table>
<br />
<table>
  <tr>
    <td colspan="2">
      Results<br />
      ===================
    </td>
  </tr>
  <tr>
    <td>
      Profit:
    </td>
    <td class="result">
      <span id="output-profit"></span>
    </td>
  </tr>
  <tr>
    <td>
      Tax:
    </td>
    <td class="result">
      <span id="output-tax"></span>
    </td>
  </tr>
  <tr>
    <td>
      Money left:
    </td>
    <td class="result">
      <span id="output"></span>
    </td>
  </tr>
</table>