<fdg:AdvancedFooterDataGrid dataProvider='{dp}'>
    <fdg:columns>
        <mx:AdvancedDataGridColumn headerText="Name" dataField="name"/>
        <mx:AdvancedDataGridColumn headerText="Price" dataField="price"/>
        <mx:AdvancedDataGridColumn headerText="Age" dataField="age"/>
    </fdg:columns> 

    <fdg:footer>
        <fdg:SummaryFooter label='Average' operation='average' precision='2'/>
        <fdg:SummaryFooter label='Max' operation='max'/>
    </fdg:footer>
</fdg:AdvancedFooterDataGrid>