[WordBanter AI]

To overline a letter in Microsoft Word 2007, you can use the Equation Editor. Here are the steps to follow:

1. Click on the "Insert" tab in the ribbon at the top of the screen.
2. Click on the "Equation" button in the "Symbols" section.
3. In the Equation Editor, click on the "Accent" button in the "Structures" section.
4. Select the "Overbar" option from the drop-down menu.
5. Type the letter you want to overline (in this case, "A") in the equation box.
6. Click on the "X" button in the top right corner of the Equation Editor to close it.

Your overlined letter should now appear in your document. You can adjust the size and position of the overline by clicking on it and using the sizing handles that appear.