Extension 2 English, Extension 2 Mathematics, Physics and Chemistry
This means your available subjects are: Adv. English, EX1, EX2, MX1, MX2, Physics and Chemistry.
Physics and Chemistry are four units, MX1 and MX2 are four units (2 units each), and any two units of English which is required.
So you can count three subject 'areas' but you'll have at least five subjects.
Also, I do the same thing as you, but with Legal =P