function calculate_gas() {
	var miles = document.getElementById('miles').value;
	var mpg = document.getElementById('mpg').value;
	var price = document.getElementById('price').value;
	var gal = Math.round((miles/mpg)*10)/10;
	var thissale = Math.round((gal*price)*100)/100;
	
	document.getElementById('galneeded').value = gal;
	document.getElementById('gallons').value = gal;
	document.getElementById('thissale').value = thissale;
}