Very slow

I am a student appearing for ipcc both groups in November 2014... Past 2 attempts I have got very less marks in accounts and advanced accounts.. My main problem is I am very slow in solving problems... Like if I solve an amalgamation 16 marks sum/or a Company final accounts or Partnership accounts.. (I was originally a science stream student) I need at least 40 minutes to solve it...coz I need to solve my sums with great care.(my conceptual knowledge in accounts is good) . Sadly, Maybe that's the quickest I can solve.. So plz help me.. I need to increase my speed and confidence in accounts.. I have scored 46and 42 in both the attempts... I can only attempt upto 50 marks in an account paper.. So like there is no scope of goin above that. I'm always scared after the accounts paper.. That will I pass in that subject or not..? However both times luckily, I passed in accounts individually.. But failed in overall. .. So should I start solving papers or something..?