Question 249783
    if the points (3, r) and (r, -1) lie on a line with slope -3/4, wat is the value of r? 
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Slope between two points on a line:
m = (y2 - y1)/(x2 - x1)
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Therefore, we have:
-3/4 = (-1 - r)/(r - 3)
Multiply both sides by 4(r-3):
-3(r-3) = 4(-1 - r)
-3r+9 = -4 - 4r
r+9 = -4
r = -13