### linear algebra point and line

I have been having difficulty with this problem. Any help would be appreciated.
Consider a line L which goes by a point Q and is parallel to a vector v. Let P be any point and let R be its mirror image across the line L.

(a) Find a formula for R starting from P, Q and vector v. Sketch your construction.
(b) Assume that P(1, 6, 2), Q(-4, 1, 2) and vector v = <-2,-1,5>. Find R.