1. The problem is to simplify the expression $6a - 3b$ using identities. 2. The expression $6a - 3b$ is a linear combination of terms and does not directly match common algebraic identities like the difference of squares or perfect square trinomials. 3. However, we can factor out the greatest common factor (GCF) from the terms. 4. The GCF of $6a$ and $3b$ is $3$. 5. Factoring out $3$, we get: $$6a - 3b = 3(2a - b)$$ 6. This is the simplified form using factoring, which is a basic algebraic identity. 7. Therefore, the simplified expression is $3(2a - b)$.