Answer :

7/10 of 80 is 56
4/5 of 80 is 64
3/4 of 80 is 60
5/8 of 80 is 50
1/2 of 80 is 40
1/4 of 80 is 20
1/10 of 80 is 8
1/8 of 80 is 10

to work these out divide the number by the denominator (bottom number) and multiply by the numerator (top number)