2/105 cannot be reduced.
6
No.
50/105 = 10/21
Yes, 2/35.
Yes: 1/7
Yes, to 16/35
105/98 reduces to 15/14. 105/7 = 15 and 98/7 = 14
105/90 = 7/6 or 11/6
1/12 can't be reduced.
Yes, 12/14 can be reduced to 6/7
12 over 5 reduced to its lowest term = 12/5 or 22/5