[" A convex lens of focal length "40cm" is in contact with a concave lens of focal length "25cm" .The power of "],[" combination is :- "]

A convex lens of focal length 40cm is in contact with a concave lens of focal length 25cm. The power of the combination is

A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is

A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is

A convex lens of Focal length of 40cm is in contact with a concave lens of focal length 25cm. The power of the combination is.

A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is ..........

A convex lens of focal length 84 cm is in contact with a concave lens of focal length 12 cm . The power of combination (in diopters) is

An eye specialist prescribes spectacles having combination of convex lens of focal length 40cm in contact with a concave lens of focal length 25cm. The power of this lens combination in diopters is