1. **Problem:** Factor the expression $15x - 12$ completely. 2. **Formula and rules:** To factor an expression, find the greatest common factor (GCF) of all terms and factor it out. 3. **Step 1:** Identify the GCF of $15x$ and $-12$. - Factors of 15: 1, 3, 5, 15 - Factors of 12: 1, 2, 3, 4, 6, 12 - Common factors: 1, 3 - Greatest common factor: 3 4. **Step 2:** Factor out the GCF 3: $$15x - 12 = 3(\cancel{5x} - \cancel{4})$$ 5. **Step 3:** Simplify inside the parentheses: $$3(5x - 4)$$ 6. **Answer:** The completely factored form is $3(5x - 4)$.