It is B because u need enough for it to do it right
Let volleyball be v and let basketball be b.
v : b = 4 : 7, b = 21
v : 21 = 4 : 7
v/21 = 4/7
7*v = 4*21
v = 4*21/7
v = 4*3
v = 12
Volleyballs are 12
Hope this helps.
Answer:
The scale factor is 
Step-by-step explanation:
Yes the figures are similar to each other. The ratio of their linear measurements is in uniform ration
The ration of radius of large cylinder (R) to that of the smaller cylinder (r) is

Like wise the ration of height of large cylinder (H) to that of the smaller cylinder (h) is

The scale factor is 
Nearest 10 is according to the last digit.
if the digit is >5, it +1 to the tenth digit. If it's <5, it will be reduced to 0.
for your case, 392, 2 < 5, therefore rounded up to nearest tenth is 390.
Because they both have two angles tbat are the same size