1. **Problem 21:** Evaluate the piecewise function $$f(x) = \begin{cases} 2x + 5 & \text{if } x \leq 2 \\ 4x + 1 & \text{if } x > 2 \end{cases}$$ at $a = 2$. 2. Since $a = 2$ satisfies $x \leq 2$, we use the first expression: $$f(2) = 2(2) + 5 = 4 + 5 = 9$$ 3. **Answer for 21:** $f(2) = 9$ 4. **Problem 22:** Evaluate the piecewise function $$f(x) = \begin{cases} 3x - 1 & \text{if } x < 1 \\ 4 & \text{if } x = 1 \\ 2x & \text{if } x > 1 \end{cases}$$ at $a = 1$. 5. Since $a = 1$ matches the middle condition $x = 1$, we use the second expression: $$f(1) = 4$$ 6. **Answer for 22:** $f(1) = 4$