Answer:

Explanation:

What does factorising mean?
- Factorising is a way of writing an expression as a product of its factors using brackets
What does expanding brackets mean?
- Expanding brackets is multiplying every term inside the bracket by the term on the outside (remember, if you multiply a negative number by another negative number, the product will be positive)
Now, expand the brackets in this expression:

Apply the difference of squares formula to factor the expression even more (also, factor out -10 from the expression by putting it in front of the brackets):

Now, factor out (b - c) from the expression:
