MS Word: How do I align the over braces of this equation?
You could:

A1. Insert > Text Box > Draw a Text Box



A2. Drag text box

A3. Paste anything you want inside
A4. Position anywhere you want in the page

OR

B1. Build a table scheme like this:



B2. Place your elements


B3. Select all, right click, cell alignment > align center



B4. Goto to borders and shanding 


B5. Select "None"


B6. Enjoy