1. **State the problem:** Solve for $u$ in an equation involving $u$ (the exact equation is not provided, so let's assume a general linear equation for demonstration: $au + b = c$. 2. **Formula and rules:** To solve for $u$, isolate $u$ on one side of the equation by performing inverse operations. 3. **Step-by-step solution:** Given: $$au + b = c$$ Subtract $b$ from both sides: $$au + \cancel{b} - \cancel{b} = c - b$$ $$au = c - b$$ Divide both sides by $a$ (assuming $a \neq 0$): $$\frac{\cancel{a}u}{\cancel{a}} = \frac{c - b}{a}$$ $$u = \frac{c - b}{a}$$ 4. **Explanation:** We first remove $b$ by subtracting it from both sides to keep the equation balanced. Then, we divide both sides by $a$ to isolate $u$. The cancellation shows the division of $a$ on both sides. 5. **Final answer:** $$u = \frac{c - b}{a}$$