Question 355257
The formula for slope (or gradient) is,
{{{m=(y[2]-y[1])/(x[2]-x[1])=1/3}}}
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{{{(5-a)/(-6-3)=1/3}}}
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{{{(5-a)/(-9)=1/3}}}
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{{{5-a=-3}}}
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Solve for {{{a}}}.