$\"\"$

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If $\"\"$ when $\"\"$ , find $\"\"$ when $\"\"$ .

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Find the constant of variation of the equation

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The statement $\"\"$ varies directly as $\"\"$ , means that when $\"\"$ increases, $\"\"$ increases by the same factor.

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Hence $\"\"$ and $\"\"$ always have the same ratio.

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The constant of variation of the equation and the slope of the line have the same value.

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$\"\"$ (Direct variation formula)

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Find $\"\"$ .

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$\"\"$ (Substitute $\"\"$ and $\"\"$ )

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$\"\"$ (Simplify)

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Therefore, the equation is $\"\"$ .

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$\"\"$

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Find $\"\"$ when $\"\"$ .

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$\"\"$ (Direct variation of the equation)

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Multiply)

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Therefore, the value of $\"\"$ is $\"\"$ .

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$\"\"$

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The value of $\"\"$ at $\"\"$ is $\"\"$ .