The sum of length, breadth and height of a cuboid is 20 cm. If the length of the diagonal is 12 cm, then find the total surface area of cuboid.

Answer: Option B

$$l$$ + b + h = 20
$$\sqrt{l^2+{\text{b}}^2+{\text{h}}^2}=12$$
$$l$$² + b² + h² = 144
2($$l$$b + bh + h$$l$$) = ?
20² = 144 + 2($$l$$b + bh + h$$l$$)
400 - 144 = 2($$l$$b + bh + h$$l$$)
256 = 2($$l$$b + bh + h$$l$$)