The power of a lens is +4D. What is the nature of lens

power 4dReal Time Live 4D Draw Results (Keputusan 4D) - Magnum 4D, Sports Toto 4D, Da Ma Cai, Sabah 88 Lotto 4D, Sarawak Special Cash Sweep 4D, STC 4D, Singapore PoolsA convex lens of power 4D is kept in contact with a concave lens of power 3D, the effective power of combination will be . View Solution; The power of a concave lens is 10 D and that of a