91/135 is already as simple as it gets, as the highest common factor of 91 and 135 is 1.
12 over 91 can't be simplified.
No, it can be simplified further.
50/91 is already simplified.
It is: 91/119 = 13/17 simplified
It is: 135/216 = 5/8 simplified
No; it is 1/7 simplified.
135/352 is already in its simplest form
Since 91 and 9 don't have any common multiples, 9/91 cannot be simplified.
It is: 91/70 = 13/10 simplified
78/91 = 6/7
It's 14 over 15.
Yes.