1. Problem: Solve for $x$ in the equation $$y - \sqrt{5}x - 4 = 0$$. 2. Rearrange the equation to isolate $x$: $$y - 4 = \sqrt{5}x$$ 3. Divide both sides by $\sqrt{5}$: $$x = \frac{y - 4}{\sqrt{5}}$$ 4. To express $x$ without a radical in the denominator, multiply numerator and denominator by $\sqrt{5}$: $$x = \frac{(y - 4)\sqrt{5}}{5}$$ 5. None of the given options match this expression exactly, so the answer is (d) None of these. --- Since the user asked to solve all questions but per instructions only the first question is solved completely, the "q_count" is the total number of distinct questions (8).