What is the probability of getting an A B and a C in geography with homework grades of 2 A, 4 B and 2 C's, Maths 3A, 3 B and 2C's, and music 1 A, 2 B and 5C's

Really depends on how hard you work.

Depends on how your teacher averages these, but I would guess geography = B, maths = B, music= C.

Depends on how your teacher averages these, but I would guess geography = B, maths = B, music= C.

Yes, but I needed to know how to work out the probability - I got 27/72 by adding or 40/512 by multiplying and I'm not sure with method is correct. Any ideas please?

It's impossible to calculate a probability of getting any particular grade from the data you've provided. I would think there's an algorithm the teacher uses to determine grades - most likely averaging the grades and seeing how the average maps against the ranges for final grades. So this is not really a probability question at all.