1. **State the problem:** Evaluate the function $f(x) = 3 - \frac{x}{10}$ at $x = -\frac{1}{2}$. 2. **Write the formula:** $$f(x) = 3 - \frac{x}{10}$$ 3. **Substitute the value:** $$f\left(-\frac{1}{2}\right) = 3 - \frac{-\frac{1}{2}}{10}$$ 4. **Simplify the fraction inside:** $$\frac{-\frac{1}{2}}{10} = -\frac{1}{2} \times \frac{1}{10} = -\frac{1}{20}$$ 5. **Rewrite the expression:** $$f\left(-\frac{1}{2}\right) = 3 - \left(-\frac{1}{20}\right) = 3 + \frac{1}{20}$$ 6. **Add the numbers:** $$3 = \frac{60}{20}$$ $$f\left(-\frac{1}{2}\right) = \frac{60}{20} + \frac{1}{20} = \frac{61}{20}$$ 7. **Final answer:** $$f\left(-\frac{1}{2}\right) = \frac{61}{20} = 3.05$$