1. **State the problem:** Solve the equation $7x + 3y - 3z = -9$ for one variable in terms of the others. 2. **Choose a variable to solve for:** Let's solve for $x$. 3. **Isolate $x$:** $$7x = -9 - 3y + 3z$$ 4. **Divide both sides by 7:** $$x = \frac{-9 - 3y + 3z}{7}$$ 5. **Simplify the expression:** $$x = -\frac{9}{7} - \frac{3}{7}y + \frac{3}{7}z$$ **Final answer:** $$x = -\frac{9}{7} - \frac{3}{7}y + \frac{3}{7}z$$ This expresses $x$ in terms of $y$ and $z$.