b = 1/2h (A + C)

My first step is to minus C on both sides so I got

b - C = 1/2h A then i flip the 1/2 to 2/1 so it's b - C = 2h A

My second step is to divide both sides by 2h..

b-c/2h = A

But in my text book it says the answer is

A = 2b/h - C

I don't get it, where did i go wrong?