1. **State the problem:** A trader wants to convert 10,000 RMB to FCFA using the function $y = \frac{x}{85}$, where $y$ is RMB and $x$ is FCFA. 2. **Formula used:** The function relates FCFA and RMB as $$y = \frac{x}{85}$$ which means RMB equals FCFA divided by 85. 3. **Solve for $x$ (FCFA):** Since we know $y = 10,000$ RMB, substitute into the equation: $$10,000 = \frac{x}{85}$$ 4. **Isolate $x$:** Multiply both sides by 85: $$x = 10,000 \times 85$$ 5. **Calculate $x$:** $$x = 850,000$$ 6. **Interpretation:** The trader needs 850,000 FCFA to pay the 10,000 RMB invoice. 7. **Graph sketch:** The function $y = \frac{x}{85}$ is a straight line passing through the origin with slope $\frac{1}{85}$. As $x$ (FCFA) increases, $y$ (RMB) increases proportionally. **Final answer:** The trader needs 850,000 FCFA.