1. **State the problem:** Simplify the expression $$\frac{5}{2} - 40$$. 2. **Recall the rules:** When subtracting a whole number from a fraction, convert the whole number to a fraction with the same denominator or convert the fraction to a decimal. 3. **Convert 40 to a fraction with denominator 2:** $$40 = \frac{40 \times 2}{2} = \frac{80}{2}$$ 4. **Rewrite the expression:** $$\frac{5}{2} - \frac{80}{2}$$ 5. **Subtract the numerators:** $$\frac{5 - 80}{2} = \frac{-75}{2}$$ 6. **Final answer:** $$\boxed{-\frac{75}{2}}$$ or as a decimal $$-37.5$$.