Conditional Formatting based on formulas

Hi All,

I have been using excel for a while now but recently started really exploring the true potential of it. I am trying to prepare a planning spreadsheet but facing an issue. I want to do a sum of all the cells in a row and compare that with the value in a single cell. If both are equal then display a certain colour else display a different colour. I am able to do this for a single row but is there a formula which does this for multiple rows together.

Example:
If K15 = sum of N15:AA15 fill the cell K15 with green colour else red
If K16 = sum of N16:AA16 fill the cell K16 with green colour else red
If K17 = sum of N17:AA17 fill the cell K17 with green colour else red

cells K15, 16, 17 etc...should not have any colour if no value is entered
btw, I use excel 2007 if that makes any difference.

Thanks in advance!

Cheers