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A gas station charges three dollars per gallon for gasoline, and six dollars for car wash.
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Daniel never washes his car there because he thinks it is too expensive, but he often buys gasoline there.
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Is the total money he spends at the station directly proportional to the amount of gasoline he buys?
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I guess first, we need to remember what directly proportional means.
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In things that are directly proportional, as one amount increases, another amount increases at the same rate.
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In our problem, we wanna know the total money spent, the total money that Daniel spends, is that directly proportional to the gas that he buys.
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The total money that Daniel spends is what Daniel buys multiplied by how much that costs.
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Daniel buys gasoline and he pays three dollars per gallon of gasoline that he buys.
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And as the amount of gasoline he buys goes up, the money that Daniel spends goes up at the same rate.
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It increases by three dollars for every gallon that he buys.
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The answer to this question is: Yes.
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The total money that Daniel spends is directly proportional to the amount of gasoline that he buys because Daniel only buys gas there.
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He does not buy a car wash.