Arguments Volume I page 27. The On Demand Lesson produces a formula 6c+3a/a/6. I don't understand this demoninator, where did it come from based on the question.

I believe you're looking at slide 59, answer choice B, where we have a + 3a / a/6
The a/6 in the denominator is c in terms of a.
Since we know that a = 6c, we can divide both sides by 6 and get to a/6 = c
We can then replace the c in the denominator with a/6

Hope this answers the question, but if not, let us know, and we'll try to help you further,

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