1. **State the problem:** Factor the expression $-9x + 30$ completely. 2. **Recall the factoring formula:** To factor an expression, find the greatest common factor (GCF) of all terms and factor it out. 3. **Find the GCF:** The terms are $-9x$ and $30$. The GCF of $9$ and $30$ is $3$. Since the first term is negative, the GCF is $-3$. 4. **Factor out the GCF:** $$-9x + 30 = -3 \times 3x + (-3) \times (-10)$$ 5. **Write the factored form:** $$-9x + 30 = -3(3x - 10)$$ 6. **Explanation:** We factored out $-3$ because it is the largest number that divides both terms and keeps the expression equivalent. Inside the parentheses, the signs change accordingly. **Final answer:** $-3(3x - 10)$