If you do mx2 than all of mathematics(2 unit) doesn't count at all, mx1 becomes 2 units worth and mx2 another 2 units totalling 4 units of maths. If you don't do mx2 but do mx1, you will only have 1 unit of mx1 and 2 units of normal maths totalling 3 units of maths. Basically this mark or any...