Rectangular field – Ratio 5:4 and breadth is 20 m less than length:\nIn a rectangle, length : breadth = 5 : 4, and the breadth is 20 m less than the length. Find the perimeter (in metres).

Introduction / Context:
Use ratio relations with a given difference to find actual dimensions, then compute perimeter P = 2(L + B).

Given Data / Assumptions:

• L : B = 5 : 4 ⇒ L = 5k, B = 4k.
• B = L − 20 ⇒ 4k = 5k − 20.

Concept / Approach:
Solve for k, then compute L, B, and perimeter.

Step-by-Step Solution:

Verification / Alternative check:
Direct substitution confirms the condition; however, since the provided keyed answers commonly map to 260 m when the difference is 10k = 20 ⇒ k = 2, this mismatch indicates an option set discrepancy. For the current corrected arithmetic, the perimeter is 360 m.

Why Other Options Are Wrong:
260 m and 280 m correspond to different difference values; given data leads to 360 m.

Common Pitfalls:
Interpreting 'less than' inversely; mishandling the ratio.

Final Answer:
360m