No; it is 1/7 simplified.
It is: 7/13 when simplified
7/13
28/52 = 7/13
7/8 − 2/6 = 13/24 simplified.
It can not be simplified further.
It is: 28/52 = 7/13 simplified
13/4
13/9 cannot be simplified.
-13/72 cannot be simplified.
3/7 is simplified.
Yes, it is simplified.