# Confuse with the solution shown in the rates of change

Hi, I just to know why the solution of this last problem in rates of change for geometry is given like this:

Let each driver drives m miles per week. The fuel used by car A is m/10 The fuel used by car B is m/30 The fuel used by car C is m/50.

Stan saves m/10 - m/30 = m/15 gallons per week.

Ximena saves m/30 - m/50 = m/75 gallons per week. This is the question being given: "Stan and Ximena both want more fuel efficient vehicles. Stan is going to switch from driving car C to car B and Ximena is going to switch from driving car B to car A. Is the following statement true or false?

Stan and Ximena will save the same amount of fuel."

I am really confuse as to why car A is m/10, car B is m/30, and car C is m/50. Even it says each represent m miles per week. Thanks for the help. 2 years, 6 months ago

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I assume you are referring to this problem.

$m/10$ represents the amount of fuel used by car A is per mileage....

- 2 years, 6 months ago

Yes.

- 2 years, 6 months ago