State sales tax

HTML

<div>
    <p><input value="" id="income"></input></p>    
</div>

<select id="states" onchange="changetax(this)">
  <option>Choose state</option>
    <option value="18">Alabama</option>
	<option value="18">Alaska</option>
	<option value="18">Arizona</option>
	<option value="18">Arkansas</option>
</select>
    
<div id="tax"></div>  
<p><button id="calculator">Calculate</button></p>

<hr />

<p>Taxed Amount: <span id="taxed"></span></p>
<p>Total: <span id="total"></span></p>

JavaScript

function changetax($this){
    
   $("#tax").text($this.value>0?("Income Tax: " + $this.value + "%") : "");
}

function calculate(e) {
    e.preventDefault();
    var income = $('#income').val();
    var tax = $('#states').val();
    var taxedAmount = income*tax/100;
    var total = parseInt(taxedAmount)+ parseInt(income);
    $('#taxed').text(taxedAmount);
    $('#total').text(total);
    return false;
}
$(function(){
$('#calculator').click( calculate );
});