I would personally say re-sit the Chemistry, I got 78 in B1, so i decided to retake, It all depends on what you want in the end! I have a feeling that the maximum mark was 45 but i can't be sure.
BTW you don't have much chance of finding your raw mark because the mark you are given is done by the UMS scale which can be a bit misleading and will change every year and will be different in every subject depending on how hard the exam was. For Example, I did P1, C1, and B1 in Jan 2008, I got something like 29/45 on C1 which you think would give me like a C, I got 94 or something on the UMS scale which meant I got an A*, It's very misleading!
EDIT: You maybe be able to get your raw marks from your teacher in september