8055/78 cannot be reduced.
54/78 = 9/13
Since both numbers are even numbers, yes 78/80 can be reduced.
13/21 can't be reduced.
3/21 can be reduced to 1/7.
21/40 cannot be reduced.
2/13
25/21 is already reduced to its lowest terms
156/74 = 78/37 which cannot be reduced further.
No.
736 and 21 are comprime so the fraction cannot be reduced.
The fraction 19/21 cannot be reduced any more.