a convex lens of power 4d is placed at a distance of 40cm

power 4dCheck 4D, 5D, 6D, Jackpot results, Sports Toto (Star, Power, Supreme Jackpot), Magnum Jackpot, Damacai 1+3D Jackpot, Live from Malaysia.6. A convex lens of power +6 D is placed in contact with a concave lens of power –4D. What will be the nature and focal length of this combination ? (a) convex, 100 cm (b) convex, 50 cm