Theres also a Casio calculator, cant remember the name, the one that has the little solar panels on the top right side, can be used to calculate formulas that inclued X in them like similtanious equations. they help alooot but im not sure if they are allowed in the exam even though i think they are, and will prob be used here. my math teacher didnt really say anything bout it even though he is very fair and quite strict.