Correct Answer - Option 3 : 135 days

**Given:**

Pen and pencil can together complete a work in 45 days

The pencil is twice efficient as pen

**Formula Used:**

Work = Efficiency × Time

**Calculation:**

Let the efficiency of Pen be p then the efficiency of Pencil is 2p

Total work = 45

The efficiency of Pen and pencil = 45/45

⇒ 1

The efficiency of pencil = 1 – p

⇒ 1 – p = 2p

⇒ p = 1/3

The efficiency of Pen = 1/3

Time = 45/(1/3)

⇒ 135 days

**∴ The pen will alone complete the work in 135 days.**