If 3n=3a-6 than the answer is B
The sides of the frame are (12+2x) and (6+2x).
Its area A is 112.
Therefore by equating:
(12+2x)*(6+2x)=112
you can get the answer for x. You will obtain a quadratic equation you have to solve.
To make enough brew for 4 people you would need:
3 frogs
4 1/2 cups of sour milk
14 gerbil tails
52 crickets
2/3 cup of eyeballs
2 Twinkies
<em>Have a luvely day!</em>