11 / 13
It is: 13/14
5/13
It reduces to 5/13
39/100 can't be reduced.
1/3
It is: 13/39 - 4/13 = 1/39
The fraction 39/200 cannot be reduced any more.
No.
It is: 13/39 - 4/13 = 1/39
Yes.
Factors of 39 (besides itself and 1) are 3 and 13. 235 isn't divisible by any of these except 1, so I don't see how it can.