1. **Stating the problem:** Solve for $x$ in each equation using transposing formulae. 2. **Part (a):** Solve $x - 4 = 9$. - To isolate $x$, add 4 to both sides: $$x - 4 + 4 = 9 + 4$$ - Simplifying gives: $$x = 13$$ 3. **Part (b):** Solve $4 - x = 11$. - To isolate $x$, subtract 4 from both sides: $$4 - x - 4 = 11 - 4$$ - Simplify: $$-x = 7$$ - Multiply both sides by $-1$ to solve for $x$: $$x = -7$$ **Final answers:** - (a) $x = 13$ - (b) $x = -7$