Bazzala, i wouldn't worry about it, I think the whole point of those computer tests, especially the stage 3 part of the computer tests are to see if you can prioritise. You have to delete the planes that are in conflict with one another and doing the arithmetic sequences is not easy although i think what they are looking for is for you to make sure the numbered aircraft are safe and if you can, do the arithmetic equations at the bottom. Not sure on this but that is how i went about it.
Good luck in March, just remember to enjoy it.