Answer:
Option D (7).
Explanation:
The formula for gradient of the straight line is given by:
m = (y2 - y1)/(x2 - x1); where (x1, y1) and (x2, y2) are two fixed points on the straight line. It is given that (x1, y1) = (4, r) and (x2, y2) = (r, 2). The gradient of the straight line is given by -5/3. To find the value of r, simply substitute all the values in the gradient equation. Therefore:
-5/3 = (2 - r)/(r - 4).
Cross Multiplying:
-5*(r - 4) = 3*(2 - r).
-5r + 20 = 6 - 3r.
-2r = -14.
r = 7.
Therefore, Option D is the correct answer!!!