var oneday = 1000 * 60 * 60 * 24;
        var adddays = oneday * 280;
        var td = new Date();

function find_due_date() {

	d = parseInt(document.getElementById('duedate').d.value);
	m = parseInt(document.getElementById('duedate').m.value);
	y = parseInt(document.getElementById('duedate').y.value);
	td.setDate(d);
	td.setMonth(m-1);
	td.setYear(y);
	td.setTime(td.getTime() + adddays);

	yr = td.getYear()+1900;
	month = td.getMonth()+1;
	date = td.getDate();
	if ((yr > 100) && (yr <1900))
		{yr = yr+1900}
	if (yr == 3900)
		{yr = 2000}
	month = td.getMonth()+1;
	date = td.getDate();
	date_text = "" +date+ "/" +month+ "/" +yr;
	document.getElementById('duedate').answer.value = date_text;
}