Keep telling yourself you know you're good enough to ace the test. Put forward questions you think the test will have and work them out in your head. Constantly reassure yourself and go in there thinking you're the bees knees. 89%, come on, that's damn good. Give yourself some credit and focus on passing and knowing you have the answers, it's just a matter of putting them on a piece of paper. Once you see how easy that is, you can relax about it! Once you know what you're doing, all that's required of you is to put it on a piece of paper, easy peasy! Not like you have to parachute down and then hanglide over crocodiles. Just take it nice and slow and focus on the task. Also, eat an apple. An apple has been proven to have a greater effect on 'waking up the body' than caffeine. Plus, it's healthy and full of yummy energy.