[рони]

qumo,

$(function() {
    var res = document.getElementById("answer"),
        price = {
            "ems": 2200,
            "avia": 2500,
            "sal": 2700,
            "parohod": 1800
        };
    res.innerHTML = price["ems"];

    function question() {
        var method = $(".find").val();
        var weight = +$("#weight").val();
        var sum = price[method];
        switch (method) {
            case "ems":
                if (weight >= .5 && weight <= 1)
                    for (var i = 50; i < weight * 100; i++) sum += 20;
                else if (weight > 1 && weight < 1.25){ /* где? */ }     
                else if (weight >= 1.25 && weight <= 2)
                    for (var i = 125; i < weight * 100; i++) sum += 24;
                break;
            case "avia":
                break;
            case "sal":
                break;
            case "parohod":
                break
        }
        res.innerHTML = sum
    }
    $("#weight").on("change", question);
    $(".find").on("change", question)
});