1. **State the problem:** Solve the equation $3(3+f) = -15$ for $f$. 2. **Apply the distributive property:** Multiply 3 by each term inside the parentheses. $$3 \times 3 + 3 \times f = 9 + 3f$$ So the equation becomes: $$9 + 3f = -15$$ 3. **Isolate the term with $f$:** Subtract 9 from both sides. $$9 + 3f - 9 = -15 - 9$$ $$\cancel{9} + 3f - \cancel{9} = -24$$ $$3f = -24$$ 4. **Solve for $f$:** Divide both sides by 3. $$\frac{3f}{3} = \frac{-24}{3}$$ $$\cancel{3}f/\cancel{3} = -8$$ $$f = -8$$ 5. **Final answer:** $$\boxed{f = -8}$$