Originally Posted by

**Uncle Peter**
The problem is, it only gives me the course rating and slope for the 3 18-hole combinations. (i.e. green/white, red/white, green/red). It doesn't give me the course rating and slope for 9-hole course.

When you combine 9 hole rounds into an 18 hole round, the rule is that rating = rating_1 + rating_2 and slope = (slope_1 + slope_2)/2 (i.e., you add the ratings and average the slopes). If you're handy with algebra you can work out the 9-hole ratings for each 9 from the info you have. I'm bored so I'll help you out here

I'll call the ratings and slopes for the various pairs R_12, R_13, R_23, and the slopes S_12, S_13, and S_23. These are for 9-holes #1 paired with #2, #1 with #3, and #2 with #3, respectively.

The ratings for each 9 are then R_1 = (R_12+R_13-R23)/2, R_2 = (R_12+R_23-R_13)/2, and R_3 = (R_13+R_23-R_12)/2.

The slopes are S_1 = S_12+S_13-S_23, S_2 = S_12+S_23-S_13, and S_3 = S_13+S_23-S_12.