2. The answer is 70

3. The answer is 33

4. The answer is 37

5. The answer is that the original question B needs to know the values of a = 3b, c = 4a and the algebraic expression (4a-9b+3c) ÷ (3a-6b+c).

6. The answer is that the square of (n-1) (n+1) = n-1is the square difference formula.