So you already have your test result?
Sounds like you're in Australia. You suffer from test stress and let your anger control you during the test. You really needed to focus more on staying relaxed. If you know you can do it normally then you have to allow yourself to remain confident during a test.
Develop a stragety to remain calm. First of all you went in with the unrealistic expectation of being able to answer all the questions. When ever you sit for a test you need to allow for the fact that there will be a few questions that you may not know the answer for... You won't necessarily get 100%. However your goal should be to do your personal best and let go of troublesome questions. That is all you can ever honestly achieve. If you had a more realistic focus you would have been able to move throught the questions easier. The first question you hit that you might not get right you got frustrated with it and stuck on it. Rather than just doing your best with it and moving on. That way ensuring that the questions you could answer without difficulty get answered. Because you had an all or nothing approach you trapped yourself.
Secondly, Given that you set yourself a target for getting into 4 unit math you overloaded yourself. That is a future goal nice one to have. However your present goal was to get the best possible passing grade for you. To bring in the worry of not being able to do 4 unit maths increases the stress that you placed upon yourself during the test.
One of your points is that you have trouble completing the questions. Were the test set in English? The English language is not your strong point and therefore you could have difficulty completing tests within the normal time for this reason. This is something you should discuss with your teacher, to help you find a strategy to deal with this problem. This might be in the form of extra exercises from old tests. They may be able to locate a tutor who can help you to learn to remain calm and focused on the goal at hand.
What other tests do you have coming up. What strategy do you already have in place? Do you know any relaxation exercises? If not would you like to learn some?
I have already pointed out the most important one thing to remember when sitting an exam. Be realistic of your expectations. You can only do your best and your best today may not be what your best was yesterday for whatever reason. (you may not be feeling well, something might be distracting you etc,). Allow for the fact that when you face a test that there will be some questions you cannot answer. Move past these quickly and cover the ones you know. You want to get your best score and you do that by answering all the questions you can answer with ease quickly, first... you can come back to the tricky ones if you still have time.
Another tip... you know at the beginning of the test how much time you have for the whole test and you also know how many questions you have...spend a few moments working out the amount of time to allow yourself for each question leaving 15 to 20 minutes spare at the end. Eg you have 60 minutes to work out 9 problems that means you allow yourself to spend only 5 minutes on each problem. If after 5 minutes you haven't completed the answer leave it and go onto the next one. Leave some space to come back to it later. You will have the opportunity to come back to it later because you spent 45 minutes answering all the questions as best you can and have 15 minutes left to go back and finish any that were incomplete. (you give yourself approx 3 minutes for each unfinished question). So have a watch on the table. Do this during practice test as well as formal tests. Kowing exactly how much time you have to spend on each question helps keep you on track to completing the test.
Alex