(c) Surface area of metal sheet = 2 (27 x 8 + 8 x 1 + 1 x 27) = 2(216 + 8 + 27) = 2 x 251 = 502 cm2 Let edge of cube which we form be x. Then, according to the question, x3 = 27 x 8 x 1 ⇒ x = 3 x 2 = 6cm ∴ Surface area of the cube = 6 x2 = 6 x 62 = 216 cm2 ∴ Required difference = 502 - 216 = 286 cm2