function calc_price(id_number)
{
	var checkbox_status = document.getElementById("cource_"+id_number).checked;
	var checkbox_value = document.getElementById("cource_"+id_number).value;
	var checkbox_value_array = new Array();
	checkbox_value_array = checkbox_value.split("|");
	var price = parseInt(checkbox_value_array[1]);
	
	var total_value = parseInt(document.getElementById("total_price").value);
	if(checkbox_status)
	{
		var new_total_price = total_value+price;
	}
	else
	{
		var new_total_price = total_value-price;
	}
	
	document.getElementById("total_price").value = new_total_price+".00";
	if(parseInt(document.getElementById("total_price").value) != 0)
	{
//		alert("100");
		document.getElementById("paid").value = "100.00"; 
	}
	else
	{
//		alert("0");
		document.getElementById("paid").value = "0.00"; 
	}
}