Formula for adding when cell is based on drop down choice

[Angel]

I am trying to modify a timesheet that has been created already. I have
added a dropdown list of codes next to each day and projects time so it can
be billed properly to the work done. Isn't there a formula to add if column b
cell = 17 then add corresponding column a cell. I hope I have worded this
correctly so someone understands what I am talking about.
Project Name 6/20/09 Code 6/21/09 Code 6/22/09 Code
Jamesville 8 17 6 14 9 12
Mission 6 10 8 17 5 14

 

[Patrick Molloy]

use formula array will let you do this, though i'm not clear with your
example

Chip Pearson (MVP) has a pretty good write up on these
http://www.cpearson.com/excel/ArrayFormulas.aspx