Two Thin Lenses,with Focal Lengths of 22

Multiple Choice

Two thin lenses,with focal lengths of 22.0 cm and -40.0 cm are placed in contact in an orientation so that their optic axes coincide.What is the focal length of the two in combination? {Hint: A thin lens is one whose thickness is negligible) .

A) 14.2 cm
B) 62.0 cm
C) 18.0 cm
D) 48.9 cm
E) ​-48.9 cm