Lei l, b and h are respectively the length, breadth and height of the cuboid, then
l = 10 cm + 10 cm 20 cm
b = 10 cm and h = 10 cm.
Now,
Surface Area of the cuboid
= 2 (lb + bh + hl)
= 2 (20 x 10+ 10 x 10+ 10 x 20) cm2
= 2 (200 + 100 + 200) cm2
= 1000 cm2.