Question

you have two lenses A and B of focal lengths +10cm and -10cm state the nature and power of each lens

Answer 1

nature of lens A will be positive and its focal length will be 0.1m or 10cm

nature of lensB will be negative  and its focal length will be -0.1 or -10cm

Answer 2

nature of A lens will be = positive
nature of B lens will be = negative