The volume of a cylinder is given by

Let
and 
The new volume becomes

So, the new volume is 8 times the original volume. In fact, volume scales linearly with the height and quadratically with the radius.
Would it help if you wrote it as
?
Then you can cross multiply if you know how to do that.
1*x = (-11)(-3)
x = 33 but what happened to the 2 minus signs?
Remember that a ( - ) times a ( - ) = a plus. The two minus signs become a plus.
The initial expression is:

So we can solve for r so:
Answer:
1) 275
2)60
Step-by-step explanation:
1) 55 x 5 =275
2) 12 x 5 = 60
<em><u>Hope it helps!</u></em>