Where should an object be placed in front of a convex lens to get a real and enlarged image of the object ?

A convex lens has a focal length of 15 cm. At what distance should an object be placed in front of the lens to get a real image of the same size of the object?

In a convex lens, if the object is placed at 2F (twice of the focal length), the image formed will be -

An object is placed between infinity and the pole (P) of a convex mirror. The position of the image is

The image formed by concave mirror is real, inverted and of the same size as that of the object. The position of the object should be

Which type of image of an object is formed by eye lens of the retina?