kvpy

Have i gone crazy or has the kvpy ones gone

question A concave lens of focal length 20 cm is given. A point object is at 10 m toward sleft of it .Find its image.

Official solution since the image is at 2f the image is also formed at 2f so 20cm to the right.But thats for convex lens isnt it ....... HEre answer should be 20/3 towards right isnt it