In the figure given below, we have 3 lenses with the same focal length 10 cm, with the distance of separation between each pair of the lenses being 30 cm. An object placed 20 cm from the first lens on the left produces an image 10 cm from the right of the rightmost lens (See Figure). After the lens assembly was moved by x cm to left, without moving the object, the image was again seen at the same location. Find x.

Satej is a twelve year old boy. He loves astronomy. Recently, he attended a sky observation workshop, organized by the Amateur astronomers Club at a hill station, During the observation session, he was introduced to Hercules, Taurus, Scorpius, Orion, Ursa Major, Gemini, Draco, Leo, Serpens and Virgo constellations. He had sketched the stick figures of some of these constellations in his note book, Unfortunately, he forgot to write the names of the constellations for his sketches ?