Area of four walls — The total area of four walls is 168 sq m. Breadth is 8 m and height is 6 m. Find the length of the room.

Introduction / Context:
The area of four walls (lateral surface area) of a rectangular room is 2(L + B) * H. With breadth and height known, solve for length from the given wall area.

Given Data / Assumptions:

• Four-wall area S = 168 m2
• B = 8 m
• H = 6 m

Concept / Approach:
Use S = 2(L + B) * H ⇒ 168 = 2(L + 8) * 6.

Step-by-Step Solution:
168 = 12(L + 8) ⇒ L + 8 = 14 ⇒ L = 6 m

Verification / Alternative check:
S = 2(6 + 8) * 6 = 2 * 14 * 6 = 168 ✔

Why Other Options Are Wrong:
14 m and 12 m are common mis-solutions from dividing once; 3.5 m and 10 m do not satisfy the formula.

Common Pitfalls:
Using floor area (L * B) or total surface area instead of four-wall area.

Final Answer:
6 meters