how use aggregate in kendo grid in mvc

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ASP.NET

MVC

aggregation

Telerik

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i want use aggregate in kendo grid but,i'm confused how to use it in my project
my code:
my model

<pre lang="c#"> public class PreOrdersViewModel
    {
        public string NameProduct { get; set; }
        public long? Price { get; set; }
        public int? Count { get; set; }
        public decimal? DisCount { get; set; }
        public long? Total { get; set; }
    }

$.ajax({
              type: "Get",
              dataType: "json",
              url: '/api/PreOrders',
              //data: { number: "test" },
              success: function (data) {
                  $('#grid22').kendoGrid({
                      dataSource: {
                          data: data
                      }, scrollable: false
                  });
              },
              error: function () {
                  alert("error");
              }
          });

<div style="width: 200px;height: 200px;">    <div id="grid3"></div></div>

i want have sum of price,count,discount and total in footer
also i want rename header column
please help me

i see document of telerik but my problem not solve:
kendo grid document
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