Remember, the volume formula of a sphere is

.
Set that equation equal to whatever volume they give you and solve for r.

=

Now solve for r! I know you can do this. If you need help, just comment.
Answer:

Step-by-step explanation:
Given



Required
Find x
If
i.e. If AB is parallel to CD, then

Substitute values for ABC and BCD

Collect Like Terms


Multiply through by 






+ 6 +

= 18
First, simplify

to

/ Your problem should look like:

+ 6 +

= 18
Second, simplify

to

/ Your problem should look like:

+ 6 +

= 18
Third, simplify

+ 6 +

to

+ 6 / Your problem should look like:

+ 6 = 18
Fourth, regroup terms. / Your problem should look like: 6 -

= 18
Fifth, multiply both sides by 7. / Your problem should look like: 42 - x = 126
Sixth, subtract 42 from both sides. / Your problem should look like: -x = 126 - 42
Seventh, simplify 126 - 42 to 84. / Your problem should look like: -x = 84
Eighth, multiply both sides by -1. / Your problem should look like: x = -84
Answer:
x = -84
Factor out 3x
Answer: 3x(x - 5)