Correct Answer - Option 4 : 27 days

**Given:**

A is twice as efficient as B.

A & B together complete the work in 18 days.

**Formula Used:**

Total work = Total efficiency × Total time

**Calculation:**

Let, efficiency of A = 2x and of B = x

Total work = Total efficiency × Total time

Total work = (2x + x) × 18

Total work = 54x

∴ Work done by A = 54x/2x = 27 days