let L be the line in R^3 that consists of all scalar multiples ofnthe vector (-1, 2, -2). Find the reflection vector v = (4, 9,1) in the line L!

I have found the projection vector of v onto L = (-4/3, 8/3, -8/3). But after this I am unable to proceed further. How do you find the reflection vector? I have searched online, come across formulas, but I dont understand!

Help please!