Subtracting values from last column in selection

I am a newbie in VBA and haven't found sample code that would help me do the following:

1. Select a range of cells, for example A1:D10
2. Subtract values in column A from D, values in column B from D, values in column C from D. So values in all columns need to be subtracted from the last column.
3. Put the calculate values in the adjacent columns, E through to G.

The number of columns and rows in the selection will vary.

Thank you in advance for your help.

Thanks a lot! The code works perfectly.