1. Problem 22 asks for a description of the algebraic expression $\frac{e}{d} - 15$. 2. This expression means you divide $e$ by $d$, then subtract 15 from the result. 3. Problem 23 asks for a description of the algebraic expression $2(d - 5)$. 4. This expression means you subtract 5 from $d$, then multiply the result by 2. 5. Problem 24 asks to evaluate $\frac{ab}{2}$ when $a=4$ and $b=5$. 6. Substitute values: $\frac{4 \times 5}{2}$. 7. Multiply numerator: $\frac{20}{2}$. 8. Simplify fraction: $\frac{\cancel{20}}{\cancel{2}} = 10$. 9. Problem 25 asks to evaluate $\frac{a^2}{5}$ when $a=4$. 10. Substitute value: $\frac{4^2}{5}$. 11. Calculate power: $\frac{16}{5}$. 12. This fraction cannot be simplified further, so the answer is $\frac{16}{5}$ or 3.2. Final answers: - Problem 24: 10 - Problem 25: $\frac{16}{5}$ or 3.2