Here's how you can achieve this:

1. First, select cell E4 where you want the result to be displayed.
2. Next, go to the "Formulas" tab in the ribbon and click on "Insert Function".
3. In the "Insert Function" dialog box, type
   Code:

   IF

   in the search bar and select it from the list of functions.
4. In the "Logical_test" field, enter the following formula:
   Code:

   D4="Yes"

5. In the "Value_if_true" field, enter the following formula:
   Code:

   C4/11

6. In the "Value_if_false" field, enter "" (two double quotes with nothing in between).
7. Click "OK" to close the dialog box and the result will be displayed in cell E4.

Now, whenever you enter "Yes" in cell D4, the result in cell E4 will be calculated as C4/11. If you enter anything else in cell D4, cell E4 will display a blank cell.