I believe it is B. I could be wrong but I am hoping that you get it right
In order to do this you have to substitute b with 9 and get 3a+9=54, now subtract 9 from both sides to leave a by itself and get 3a=45, now divide 3 in both sides to leave a by itself and get a=15
Hope this helps
i would probably use an iv or a blood simple
