Answer:
3.14 * r^2 * h
Step-by-step explanation:
3/4 =3/4
4/6= 2/3
8/18= 4/9
9/15=3/5
7/21= 1/3
10/12= 5/6
4/8= 1/2
10/16=5/8
15/20= 3/4
3/30=1/10
8 7
Because the number will be positive