Can you give me some questions related to reflection and magnification of concave and convex mirror

Here are some questions related to reflection and magnification of concave and convex mirrors:

1. An object is placed $20 \text{ cm}$ in front of a concave mirror. If the focal length of the mirror is $15 \text{ cm}$, calculate the position and nature of the image formed. Also, determine the magnification.

2. A convex mirror has a focal length of $10 \text{ cm}$. An object is placed $15 \text{ cm}$ in front of the mirror. Find the position, nature, and magnification of the image.

3. A concave mirror produces a real image that is three times the size of the object. If the object is placed $18 \text{ cm}$ from the mirror, what is the focal length of the mirror?