First of all, sorry if i posted this in the wrong forum. This is for my Discrete preparation course for univerisity and there was no Discrete forum under the highschool heading

Anyways here is the question:

Vectors 'a' and 'b' are drawin tail-to-tail. Vector 'c' is the reflection of 'a' in the line containing vector 'b'. Express 'c' as a linear combination of 'a' and 'b'.

I tried showing it through the use of the projection of a vector formula but I keep getting stuck. Could any of you please offer some guidance or a suggestion on where to start?