Responding to Essay Qs w/ ('relative') calculations that also require "justification"?

Hey everyone, I’m a 2nd time L3 candidate after not passing last year & have a quick question about what people would do for answering questions like last year’s (2011) Economics essay question #4-E - specifically, the “justification” - in the most efficient manner possible that should / could still be expected to get full-points.

The answer key response for this one is about as miserably-long as my actual response was at the time, & that repeated pattern throughout the morning session absolutely destroyed me time-wise, & thus, test-wise. I tend to drag out writing in all mediums, so I have a real problem with otherwise easy ‘essay’ questions like this where the calculation AND your response (here, circled) not only clearly exhibit knowledge of the material in question, but also plainly leave nothing else to be said that could succinctly serve as “justifying the answer”. I circled ‘Fairly Valued’, then wrote out the simple calculation I’d already done in my head, then circled the equals sign… Other than writing out the full formula using variables before that, what in the world was a reasonable expectation for a candidate having to write out to then “justify” that?? Even if the result/answer hadn’t been a fair valuation, the issue still would’ve existed.

Has anyone consistenly noticed any prep writer’s “FTE” suggested answers for these type of problems (requiring a calculation, possibly a response, and then a seemingly needless explanation/justification) where they write out something really to the point, like the equation once with the values already plugged in, semicolon, then “Justified blah blah of X > Model’s blah blah of Y, therefore X blahly-valued. [Period.]”?