Sarah drove 40 miles per hour. In 3 hours, Sarah drove 120 miles. Which is a valid proportion to represent this description?

A valid proportion compares the same units in the same order. Sarah’s rate is 40 miles per 1 hour, and her total distance and time are 120 miles in 3 hours, so 40/1 = 120/3. This matches choice D, “40 over 1 is equal to 120 thirds.”

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