Please help me solve The focal length is 79 cm.

Given:
The focal length is f = 79 cm
Also,
[tex]q_{min}=-19\text{ cm}[/tex]Required: p_min
Explanation:
The p_min can be calculated as
[tex]\begin{gathered} p_{min}=\frac{fq_{min}}{q_{min}-f} \\ =\frac{(-79\text{ cm})(-19\text{ cm})}{-19\text{ cm}-(-79\text{ cm})} \\ =25.02\text{ cm} \end{gathered}[/tex]Final Answer: The value of p_min is 25.02 cm.