80 over 99 is already in lowest terms.
55 over 80 at its lowest terms is 11/16
it is 4/5
9/10
3/8
3/4
3/8
63/80 is in lowest terms. 80=2x2x2x2x5 2 and 5 do not got into 63 without a remainder.
It is: 80/100 = 4/5 in its lowest terms
It is: 56/80 = 7/10 in its lowest terms
0.7125 = 57/80 in its lowest terms
80% as a fraction in lowest terms is 4/5