Surface Area of a Cuboid

 Hi folks,
There's been a bit of confusion with the surface area of a cuboid so attached below are videos of Q6 a,b and c.  This would a challenging concept to understand if we were in the classroom never mind trying to do it over video so don't be disheartened if you had difficulty.  Tomorrow we might do some more for practice. In secondary school they will give you a formula to help solve these kinds of problems so I'll try and explain that tomorrow too. 
​Keep up the great work!