1. **State the problem:** Solve for $x$ in terms of $a$ from the equation: $$7a \cdot 9b - 1 \cdot x + 9a - 1 - 0 = 0$$ 2. **Rewrite the equation clearly:** $$7a \times 9b - x + 9a - 1 = 0$$ 3. **Simplify the terms:** $$63ab - x + 9a - 1 = 0$$ 4. **Isolate $x$ on one side:** $$-x = -63ab - 9a + 1$$ 5. **Multiply both sides by $-1$ to solve for $x$:** $$x = 63ab + 9a - 1$$ 6. **Express $x$ in terms of $a$ (and $b$ as given):** $$\boxed{x = 63ab + 9a - 1}$$ This is the solution for $x$ in terms of $a$ and $b$.