Where should an object be placed so that its real and same size image is formed?

A diverging lens of focal length 12 cm and a converging mirror of focal length 10 cm are placed coaxially at a separation of 5 cm. Where should an object be placed so that a real image is formed at the object itself ?

(a) A point source S is placed at a distance of 15 cm from a converging lens of focal length 10 cm on its principal axis, where should a diverging mirror of focal length 12 cm be placed so that a real image is formed on the source itself? (b) A diverging lens of focal length 20 cm and a converging mirror of focal length 10 cm are placed coaxially at separation of 5 cm. Where should an object be placed so that a real image is formed at the object itself? (c) A converging lens of focal length 12 cm and a diverging mirror of focal length 7.5 cm are placed 5.0 cm apart with the principal axis coinciding where should an object be placed so that its image falls on itself?

There is a sphere of radius R and refractive index mu . At what distance from the surface of sphere should an object be placed so that real image is formed at the same distance from the sphere ?

Rays from Sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed so that size of its image is equal to the size of the object ?

The focal length of a concave mirror is 12 cm . Where should an object of length 4 cm be placed so that a real image of 1 cm length is formed ?