12 over 91 can't be simplified.
50/91 is already simplified.
No.
It is: 91/119 = 13/17 simplified
132/240 = 11/20
42/132 = 7/22
9/132 = 3/44
No; it is 1/7 simplified.
4/9
31/66
Since 91 and 9 don't have any common multiples, 9/91 cannot be simplified.
It is: 48/132 = 4/11 simplified