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.
50/91 is already simplified.
No, it can be simplified further.
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.