[qumo]

Немного отредактировал

$(function() {
			    var price = document.getElementById('answer'),
			    ems_price = 2200;
				avia_price = 2500;
			    sal_price = 2700;
			    parohod_price = 1800;
				price.innerHTML = ems_price;
				
				function question() {
				  var method = $('.find').val();
				  switch(method) {
					case 'ems':
					  var weight = +$('#weight').val();
					  var sum = ems_price;
					  if(weight >= 0.5 && weight <= 1){
					    for (var i= 50; i< weight*100; i++)  {
						  sum += 20;
						};
					    price.innerHTML = sum;
					  };
					  if(weight >= 1.25 && weight <= 2){
					    for (var i = 125; i< weight * 100; i++)  {
						   sum += 24;
						};
						price.innerHTML = sum;
					  };
					break;
					
					case 'avia':
					  price.innerHTML = avia_price;
					break;
					
					case 'sal':
					  price.innerHTML = sal_price;
					break;
					
					case 'parohod':
					  price.innerHTML = parohod_price;
					break;
				  }
				}
				$('#weight').on("change", question);
				$('.find').on("change", question);
			  });