MainWindow.xaml

<Window
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid" x:Class="CustomFilterOperationExample.MainWindow"
    xmlns:local ="clr-namespace:CustomFilterOperationExample"
        Title="MainWindow" Height="350" Width="525">
    <Window.DataContext>
        <local:TaskNums/>
    </Window.DataContext>
    <Grid>

        <dxg:GridControl ItemsSource="{Binding List}" AutoGenerateColumns="AddNew">
            <dxg:GridControl.View>
                <dxg:TableView AllowConditionalFormattingMenu="True" x:Name="table1">
                    <dxg:TableView.FormatConditions>
                        <dxg:FormatCondition Expression="Function([FirstNum], [SecondNum], [TherdNum])">
                            <dxg:Format Background="LimeGreen" Foreground="White"/>
                        </dxg:FormatCondition>
                    </dxg:TableView.FormatConditions>
                </dxg:TableView>
            </dxg:GridControl.View>
        </dxg:GridControl>
    </Grid>
</Window>