I was at OASC in December, and the maths that I had to do was not too taxing. Although, this is obviously my own opinion, and there is certainly not much chance of you getting the same problems that I did. When you're faced with devisions like 40/120, cancelling down will make this devision a dream. First of all cancel by 10, giving 4/12, then by four, giving 1/3, which is 33%. Learn how to convert fractions/percentages of hours/minutes into hours and minutes. In this case, for instance, 33.3% or 1/3 of an hour is 20 minutes, a minute, 20 seconds.
PM if you are still in desperate need of help. Work hard, and you will get it, I did.
TMA