A a,b,c ∈
2a + b + =12 ⇒ max (c) = ?

Yes you are correct because the only thing you need to do to get the reflexive in this problem is to make the y axis the opposite of what it normally is like for example the reflexive of (1,2) would be (-1,2) when it is going horizontal but when it is not it will be the x axis reversed.