Problem Solving

I have attached a question from GMAT Prep Test 1. Please advise how to achieve the result.

Answer: D

Thank you,
K

M = 9 x 6 = 54.

M is even. Therefore you use 1/2m which is 1/2 * 54 = 27

I see what I did wrong, I didn't understand the box was part of the function.

So it's f9 x f6. so 9 is odd so it's (9 x 3) and 6 is even so it (6/2). That's 27 x 3 which is 81.

So the answer choices are all in a function mood.

f27 is odd so it's 27 x 3 which is 81.

So f27 = 81 and that's why it's the answer. My wrong way just so happened to get to the right answer by mistake.