igor.morgunov,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script>
$(function() {
var discount = $(".discount");
discount.change(function() {
var len = discount.filter(":checked").length;
var result = {0 : 0, 1 : 15000, 2 : 21000, 3 : 27000}[len]
$('#result .montage').html(result);
})
});
</script>
</head>
<body>
<div class="header-content-page">
<div class="header-name7">РАСЧЕТ СТОИМОСТИ</div>
<div class="header-name7-black">ВЫБОР МОЩНОСТИ</div>
<div class="header-main-form">
<div class="btn-group" data-toggle="buttons">
<label class="btn active" id="option-00">
<input type="radio" name="options" id="option-0" value="0" checked>
1 вкладка
</label>
<label class="btn" id="option-01">
<input type="radio" name="options" id="option-1" value="1">
2 вкладка
</label>
<label class="btn" id="option-02">
<input type="radio" name="options" id="option-2" value="2">
3 вкладка
</label>
</div>
<div class="check-group">
<label id="label-0" class="clearfix" for="check-0">
<input id="check-0" type="checkbox" checked />1й
<span class="float-right"></span>
</label>
<label id="label-1" class="clearfix" for="check-1">
<input id="check-1" type="checkbox" class="discount" />2й
<span class="float-right"></span>
</label>
<label id="label-2" class="clearfix" for="check-2">
<input id="check-2" type="checkbox" class="discount" />3й
<span class="float-right"></span>
</label>
<label id="label-3" class="clearfix" for="check-3">
<input id="check-3" type="checkbox" class="discount" />4й
<span class="float-right"></span>
</label>
<label id="label-4" class="clearfix" for="check-4">
<input id="check-4" type="checkbox" />5й
<span class="float-right"></span>
</label>
<label id="label-5" class="clearfix" for="check-5">
<input id="check-5" type="checkbox" />6й
<span class="float-right"></span>
</label>
</div>
</div>
</div>
<div id="result">
<div class="montage"></div>
</div>
</body>
</html>