find the value of (r) so that the line through (-4, 3) and (r, -3) has a slope of 2/3
When you have the points (x1, y1) amd (x2, y2), then the slope of the line between them is given by
m = (y2 - y1) / (x2 - x1)
Since we have (x1, y1) = (-4, 3) and (x2, y2) = (r, -3), then the slope is
m = (-3 - 3) / (r - (-4)), i.e.
2/3 = -6 / (r + 4)
2(r + 4) = -18
r + 4 = -9
r = -13