A bicycle pump holds 0.42 L of air at 100 kPa…

Step 1. Boyle's law. $p_1V_1 = p_2V_2$.

Step 2. Part (a). We want $p_2$, so $p_2 = \dfrac{100\ \text{kPa} \times 0.42\ \text{L}}{0.14\ \text{L}} = 300$ kPa.

Step 3. Part (b). We want $V_2$, so $V_2 = \dfrac{100\ \text{kPa} \times 0.42\ \text{L}}{250\ \text{kPa}} = 0.168$ L.