792
1188 is a common denominator for 9,11,12
since 9 and 11 have no common factors, the LCD is 99
If 9, 11, and 16 are all denominators, you could multiply them together to come up with a common denominator of 1,584.
198
693
1
LCD(8, 11, 9) = 792
5148
990
1980
The least common denominator is 30. 9/10 = 27/30
The GCF is 1.