Example 2: The amount of gas used varies directly with the number of miles a car travels. 

  1. What is the constant of proportionality in this example?  HINT: Stop the car at various times to see the values of the two quantities.

  2. Use your answer from #1 above to compute how much gas will have been used after driving 200 miles. Then, click on the "Show graph" button to check your solution. Challenge: How is the constant of variation related to the graph?

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direct_variation_cleaner