Question 231847
How to find an equation of the line passing through the pair of points in the form of Ax+By=C? 
Equation 
(-7,8), (-8,-5) 
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slope = (8--5)/(-7--8) = 13/1 = 13
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Form: y = mx + b
You have m=13 and y = 8 when x = -7 ; solve for "b":
8 = 13*-7 + b 
b = 99
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Equation:
y = 13x + 99
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Rearrange:
13x - y = 99
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Cheers,
Stan H.