1. **State the problem:** Expand the expression $3(3a + 2b - c)$. 2. **Formula used:** Use the distributive property of multiplication over addition/subtraction: $$a(b + c + d) = ab + ac + ad$$ 3. **Apply the distributive property:** Multiply each term inside the parentheses by 3: $$3 \times 3a + 3 \times 2b + 3 \times (-c)$$ 4. **Calculate each multiplication:** $$9a + 6b - 3c$$ 5. **Final answer:** The expanded form of $3(3a + 2b - c)$ is $$9a + 6b - 3c$$.