Answer:
the second one is 20 i think
Step-by-step explanation:

is the same thing as

and

Therefore, the first option is correct.
Answer:
The Answer for a is $175
Step-by-step explanation:
Thats all I know sorry
Answer:
4:25
Step-by-step explanation:
Given that,
r₁ = 15 inches, r₂ = 6 inches
The area of the cylinder is given by :

The ratio of surface areas of two cylinders,

Hence, the required ratio is 4:25.
A graphing calculator or spreadsheet program can do this for you. Below is a plot from the Desmos on-line graphing calculator.