A 6.47-mm-high firefly sits on the axis of, and 13.1 cm in front of, the thin lens A, whose focal length is 6.19 cm. Behind lens A there is another thin lens, lens B, with focal length 27.9 cm. The two lenses share a common axis and are 55.7 cm apart. Is the image of the firefly that lens B forms real or virtual?