Hi Stacy,

I guess we could try the footerCallBack option of DataTables:

https://datatables.net/examples/advanced_init/footer_callback.html

To use this with KoolReport's DataTables widget please try this call:

    \koolreport\datagrid\DataTables::create(array(
        ...
        "options" => array(
            "footerCallback" => "function ( rows, group ) {
                //calculate sum(start), sum(end) here and put sum(start)/sum(end) at end column index footer
            ",
        ),
    ));

Let us know if you have any difficulty apply this. Thanks!