function Calculate()
  {
    // calculate each line total
    document.forms['Reservation'].elements[24].value = document.forms['Reservation'].elements[19].value * document.forms['Reservation'].elements[13].value;
    document.forms['Reservation'].elements[25].value = document.forms['Reservation'].elements[20].value * document.forms['Reservation'].elements[14].value;
    document.forms['Reservation'].elements[26].value = document.forms['Reservation'].elements[21].value * document.forms['Reservation'].elements[15].value;
    document.forms['Reservation'].elements[27].value = document.forms['Reservation'].elements[22].value * document.forms['Reservation'].elements[16].value;
    document.forms['Reservation'].elements[28].value = document.forms['Reservation'].elements[23].value * document.forms['Reservation'].elements[17].value;

    document.forms['Reservation'].elements[37].value = document.forms['Reservation'].elements[34].value * document.forms['Reservation'].elements[30].value;
    document.forms['Reservation'].elements[38].value = document.forms['Reservation'].elements[35].value * document.forms['Reservation'].elements[31].value;
    document.forms['Reservation'].elements[39].value = document.forms['Reservation'].elements[36].value * document.forms['Reservation'].elements[32].value;

    // total costs
    document.forms['Reservation'].elements[29].value = parseFloat(document.forms['Reservation'].elements[28].value)
    + parseFloat(document.forms['Reservation'].elements[27].value)
    + parseFloat(document.forms['Reservation'].elements[26].value)
    + parseFloat(document.forms['Reservation'].elements[25].value)
    + parseFloat(document.forms['Reservation'].elements[24].value);

    document.forms['Reservation'].elements[40].value = parseFloat(document.forms['Reservation'].elements[39].value)
    + parseFloat(document.forms['Reservation'].elements[38].value)
    + parseFloat(document.forms['Reservation'].elements[37].value);

    // total people
    document.forms['Reservation'].elements[18].value = parseFloat(document.forms['Reservation'].elements[13].value)
    + parseFloat(document.forms['Reservation'].elements[14].value)
    + parseFloat(document.forms['Reservation'].elements[15].value)
    + parseFloat(document.forms['Reservation'].elements[16].value)
    + parseFloat(document.forms['Reservation'].elements[17].value);

    document.forms['Reservation'].elements[33].value = parseFloat(document.forms['Reservation'].elements[30].value)
    + parseFloat(document.forms['Reservation'].elements[31].value)
    + parseFloat(document.forms['Reservation'].elements[32].value);
  }