Sangeetha Pulapaka
0

STEP 1: Recall what is the slope of a line

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STEP 2: Recall the slope formula

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STEP 3: Calculate the slope

Take the slope formula and plug in the slope and both pairs of (xy) coordinates. Then solve for r.

                                  slope = \frac{y_{2}-y_{1}}{x_{2} - x_{1}}

Plugging in slope m = -1 and x_{1} = 2, y_{1} = r, x_{2}= -1, y_{2} = 7

-1 = \frac{7 -r}{-1-2}

-1(-1 -2) = 7 - r

3 = 7 - r

r = 4