Rectangular field — Length:breadth = 5:4 and breadth is 20 m less than length. Find the perimeter.

Introduction / Context:Combine a ratio with a difference condition to solve for actual side lengths, then compute perimeter.

Given Data / Assumptions:

• L:B = 5:4
• L − B = 20 m

Concept / Approach:Let L = 5k, B = 4k ⇒ L − B = k = 20 ⇒ k = 20. Then find L and B and perimeter P = 2(L + B).

Step-by-Step Solution:L = 100 m, B = 80 mP = 2(100 + 80) = 360 m

Verification / Alternative check:Ratio holds (100:80 = 5:4) and difference is 20.

Why Other Options Are Wrong:260, 280, 300 m do not match 2(L + B) with the solved dimensions.

Common Pitfalls:Using 5k + 4k = 20 instead of 5k − 4k = 20.

Final Answer:360 m