function cal_car() {
	if(!document.getElementById) return;
	if(!nu()) return;
  var result = "";
	if(document.carForm.car_sel.selectedIndex == 1 ){
		result = parseInt(parseInt(document.carForm.car_mile.value) * 0.91);
	} else {
		result = parseInt(parseInt(document.carForm.car_mile.value) * 1.15);
	}
	document.getElementById('calculator_results').innerHTML = '<b>Your daily commute produces <span style="color: #b10d1d">' +result+ '</span> pounds of CO<sub>2</sub></b><br><br><b>The average UK household emits 60 pounds of CO<sub>2</sub> each day &mdash; the same as a 65-mile round trip in a car. How does your commute compare?</b>';
}


function cal_plane() {
	if(document.planeForm.plane_sel.selectedIndex == 1 ){
	  document.planeForm.plane_ems.value = parseInt(160)
	} else if (document.planeForm.plane_sel.selectedIndex == 2) {
	  document.planeForm.plane_ems.value = parseInt(360)
	} else if (document.planeForm.plane_sel.selectedIndex == 3) {
	  document.planeForm.plane_ems.value = parseInt(975)	
	} else {
	  document.planeForm.plane_ems.value = parseInt(1950)
	}
}

function nu() {
  if(isNaN(document.carForm.car_mile.value) || document.carForm.car_mile.value == ""){
    alert("Please enter number!");
    document.carForm.car_mile.focus();
    return false;
  }
  return true;
}

function nu2() {
  if(isNaN(document.planeForm.plane_mile.value) || document.planeForm.plane_mile.value == ""){
    alert("Please enter number!");
    document.planeForm.plane_mile.focus();
    return false;
  }
}