Question

If the surface area of a cube is 18sq.cm what is the surface area of a cuboid formed by joining 3 of these cubes

Answer 1

in the linear cubiod, three cubes share two faces at each junction, there are two juncions, or 4 surfaces not exposed as surface.

Area of each face joine=18/6 =3cm^2
New surface area=18*3-4*3 cm^2

Answer 2

Area of each face joine =18/6=3cm^2
New surface area =18*3-4*3cm^2 =42