Rectangle — Length : Breadth = 2 : 1 and Breadth 5 cm Less: The ratio L : B is 2 : 1. If breadth is 5 cm less than length, find the perimeter (in cm).

Introduction / Context:
This is a straightforward system using a ratio and a difference. After finding the actual sides, compute the perimeter using P = 2(L + B). Units remain in centimetres throughout.

Given Data / Assumptions:

• L : B = 2 : 1 ⇒ L = 2k, B = k
• B = L − 5
• Perimeter P = 2(L + B)

Concept / Approach:
From B = L − 5 and L = 2k, B = k, we get k = 5. Substitute to find sides and then compute the perimeter.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

• 25 and 28 miss the 2× sum step.
• 35 and 40 require different side lengths than given.

Common Pitfalls:

• Treating the ratio as L − B rather than L : B.

Final Answer:
30 cm.