Excel 2007 : Formatting a cell to match other cells (if they match)

Hi,
I have a question - I would like to format a cell (its fill in colour) to match two other cells (assuming they match). this is a resource pipeline view - cell A3 has a specific project (highlighted in yellow), cell a4 has another (highlighted in blue), etc. dynamic list of projects that can have upto 12 projects (some day more). Resources are listed in rows 18 through 33. dates are listed in columns C through CZ. When I assign a resource to a project for a specific date i highlight the approprate cells with the corresponding color for the project. what i would like excel to do is automatically highlight the project line as well - rows 3 through 10.

the way i see it, i would need a fomula in cell 3C; if format of 3A=18C or 19C or 20C or 21C or 22C or 23C, etc., then format 3C is the same as 3A.

any direction or help would be great,
thanks,
Teddy