Correct Answer - Option 1 : 45 km/h

**Calculation**:

Let speed of the train be x km/hr and length of the train be d m.

As we know

Distance = Speed × Time

⇒ Distance = x × 5/18 × 20 ---(1)

Again,

Distance = 18 × (x + 5) × 5/18 ---(2)

From equation (1) and equation (2)

⇒ x × 5/18 × 20 = 18 × (x + 5) × 5/18

⇒ 20x = 18x + 90

⇒ 20x – 18x = 90

⇒ 2x = 90

⇒ x = 90/2

⇒ x = 45 km/hr