Topic : reflection of light by spherical mirrors

At what distance from a convex mirror of focal length 2.5 m should a small object be kept so that its image has height of half of original height of object

An object is placed at 40 cm from a concave mirror of focal length 30 cm. The image is

An object is placed at a distance 2f from the pole of a convex mirror of focal length f. The linear magnification is

The focal length of a concave mirror is 30 cm. Find the position of the object in front of the mirror (on axis), so that the image is three times the size of the object.