Correct Answer - Option 2 : 2 : 3

**Given:**

Let number of pens and number of notebooks in a box be a and (100 - a) respectively.

**Calculation:**

⇒ 20 × a + (100 - a) × 30 = 2600

⇒ 20a + 3000 - 30a = 2600

⇒ a = 40

The number of pens in a box = 40

The number of notebooks in a box = 100 - 40 = 60

**∴ Required ratio = 40 : 60 = 2 : 3.**