Correct Answer - Option 3 : 27 days

**Given:**

Efficiency of A = 2 × Efficiency of B

They together can complete the whole work in 18 days

**Concept Used:**

Work = Efficiency × Time

**Calculation:**

We have

Efficiency of A : Efficiency of B = 2 : 1

Efficiency of (A + B) = 3

Total Work = 3 × 18 = 54 units

A alone can do this work in 54/2 days [Total work/efficiency of A]

⇒ 27 days.

**∴ The time taken by A to complete the work is 27 days.**