Three cubes of me A.

B.

C.

D.

Here, the volume of three cubes = volume of the new cube

Volume of a cube = (side)³

Volume of three cubes = (3)³ + (4)³ + (5)³= (27 +64+ 125) cm³ =216 cm³

⇒ Volume of new cube = 216 cm³= (side)³

⇒ (side)³ = (6 cm)³

⇒ side = 6cm

Lateral surface area = 4(side)² = 4(6)² = 144cm²