1. **State the problem:** We are given the equation $$\frac{20}{p} = \frac{20}{q} - \frac{20}{r} - \frac{20}{s}$$ and asked to find an expression equivalent to $q$. 2. **Rewrite the equation:** Start by isolating terms involving $q$: $$\frac{20}{p} = \frac{20}{q} - \frac{20}{r} - \frac{20}{s}$$ 3. **Combine the right side:** $$\frac{20}{q} = \frac{20}{p} + \frac{20}{r} + \frac{20}{s}$$ 4. **Factor out 20 on the right side:** $$\frac{20}{q} = 20\left(\frac{1}{p} + \frac{1}{r} + \frac{1}{s}\right)$$ 5. **Divide both sides by 20:** $$\frac{1}{q} = \frac{1}{p} + \frac{1}{r} + \frac{1}{s}$$ 6. **Find common denominator on the right side:** $$\frac{1}{q} = \frac{rs + ps + pr}{prs}$$ 7. **Invert both sides to solve for $q$:** $$q = \frac{prs}{rs + ps + pr}$$ **Final answer:** $$q = \frac{prs}{pr + ps + rs}$$ This matches the expression $$\frac{prs}{pr + ps + rs}$$ which is equivalent to $q$. **Note:** The highlighted choice "20(p + r + s)" is not equivalent to $q$ based on this derivation.