How far an object should be placed from the pole of a concave mirror of focal length 20cm to form a real image whose size is 1/5 the size of the object.

The question was asked by jasleen Kaur Bhasin

How far an object should be placed from the pole of a concave mirror of focal length 20 cm to form a real image whose size is 1/5 the size of the object?

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