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General Equation
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y = mx + c
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Substitute Slope into equation
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y = -3x + c
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Find y-intercept
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at point (7, 8), x = 7 when y = 8
8 = -3(7) + c
8 = - 21 + c
c = 8 + 21
c = 29
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Substitute y-intercept into the equation
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y = -3x + 29
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Answer: y = -3x + 29
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