I need help setting up the following Column Width macro in Excel:

1. The "width" for Columns A, B, C, D should total 40.
2. Columns B, C, D have been "autofit" based on the data entered.
3. How would I set Column A "width" for all columns to still equal 40.

For example:

The new values are as follows:
Column B = 13
Column C = 10
Column D = 5

How would I set Column A "width" to 40 - (13,10,5)