how set selected item or selected value in comboBox (C# wpf)

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C#

WPF

hi,
i fill my combobox with the following code:

<pre> var result = (from a in  dbContext.tbl_Representaion select a).ToList();
            cmbRepresentation.ItemsSource=result;
            cmbRepresentation.DisplayMemberPath = "Name";
            cmbRepresentation.SelectedValuePath = "ID";</pre>

and myXaml Code:

<pre> <ComboBox FlowDirection="RightToLeft" Height=" 25" HorizontalAlignment="Right" Margin="0,6,5,0" Name="cmbRepresentation" SelectedIndex="-1" VerticalAlignment="top" Width="100" SelectionChanged="cmbRepresentation_SelectionChanged" SelectedValue="{Binding Path=SelectedValue, UpdateSourceTrigger=PropertyChanged}" SelectedItem="{Binding SelectedItem}">
           
        </ComboBox

>

now ,how when load data ,I display item for ID required with selected value or selected item(not selectedIndex)?