ExplanationAs soon as you see variables in the answer choices, set up your scratch paper to Plug In.

Start with x = 5, so it takes 1 minute to knit 1 row. Now make y = 2. A scarf 2 feet long means Mariko has to knit 200 rows, which will take 200 minutes; since the problem asks how many hours it will take, your target answer is \(\frac{200}{60}=3\frac{1}{3}\).

Now plug your values into the answer choices; only choice (A) hits your target. Choices (C) and (E) are clearly too small, and choice (D) is a fraction, so you may not have to calculate all the choices.

Hence option A is correct!
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Sandy

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