1. **Problem Statement:** Messi has a function relating cost $x$ to sale price $f(x)$ given by $$f(x) = \frac{12x}{10} + 2.$$ He finds out that an extra 4 is being charged for each product, so he wants to adjust the function to fix this overcharge. 2. **Understanding the problem:** The original function adds 2 to the scaled cost. The extra charge of 4 means the current sale price is 4 more than it should be. 3. **Goal:** We want a new function $g(x)$ that represents the correct sale price without the extra 4 added. 4. **Adjusting the function:** Since the original function adds 2, and there is an extra 4 added on top of that, the total extra is $2 + 4 = 6$. 5. **Correct function:** To fix the overcharge, subtract 4 from the original function: $$g(x) = f(x) - 4 = \left(\frac{12x}{10} + 2\right) - 4 = \frac{12x}{10} - 2.$$ 6. **Matching with options:** The corrected function is $$f(x) = \frac{12x}{10} - 2,$$ which corresponds to option C. **Final answer:** Option C) $$f(x) = \frac{12x}{10} - 2.$$