IF AND function

I received 3 responses, none really worked as I intend.  I did not explain my problem very well.  I have attached my spreadsheet, which may help.

This is a golf scoring sheet for my golf club.

Our members have the option of playing from white tees, which is where most play.

Some choose to play from the red tees.

The handicaps are different...column Y is white and Z is red.

The Net score from red tees is X - Z

The net score from white is X - Y

So the formula I have in column AC works fine when someone plays from white tees.

The formula in column AD also works when someone plays for red tees.....our scorer enters r in column C to enable the calculation. 

But here's what I would like to accomplish....when someone plays from red tees, I would like the white score to disappear and show only the red score.

An even better solution, if it's possible, is to have only 1 column for net score instead of 2 columns. So the column AC would calculate X-Y when column C is empty, and it would calculate X-Z when column C contains r...or R....or any data for that matter.  Column AE is formatted to highlight those who play from red, column AC is formatted to highlight scores of 72 or less, to more easily spot the lowest scores and the winners.