(a) Find the image A' of the point A(1, 6, 3) in the line $\frac{x}{1} = \frac{y - 1}{2} = \frac{z - 2}{3}$. Also, find the equation of the line joining A and A'. OR (b) Find a point P on the line $\frac{x + 5}{1} = \frac{y + 3}{4} = \frac{z - 6}{-9}$ such that its distance from point Q(2, 4, -1) is 7 units. Also, find the equation of line joining P and Q.