1. **State the problem:** We are given a function that models the credit left on a prepaid phone card after making calls. The function is: $$C(x) = 15.00 - 0.10x$$ where $x$ is the number of minutes of calls made, and $C(x)$ is the remaining credit in dollars. We need to find the credit left after Jose uses the card for 40 minutes. 2. **Use the formula:** Substitute $x = 40$ into the function: $$C(40) = 15.00 - 0.10 \times 40$$ 3. **Calculate the product:** $$0.10 \times 40 = 4.00$$ 4. **Subtract to find remaining credit:** $$C(40) = 15.00 - 4.00 = 11.00$$ 5. **Interpretation:** After 40 minutes of calls, Jose has 11.00 dollars of credit left on his prepaid phone card. **Final answer:** $$\boxed{11.00}$$