Correct Answer - Option 1 : 80 km

**Given:**

Steamer time taken in downstream = 4hours

Steamer time taken in upstream = 5 hours

**Boat and stream method **

Let the speed of streamer in still water = x kmph

**∴** Rate downstream = (x + 2) kmph

Rate upstream = (x - 2) kmph

Distance covered downstream and upstream are equal

**Calculation**

⇒ 4(x + 2) = 5(x - 2) ⇒ 4x + 8 = 5x - 10

⇒ 5x - 4x = 10 + 8 ⇒ x = 18

**∴** Rate downstream = 18 + 2 = 20 kmph

Therefore, the required distance

= Speed downstream × Time

**= 20 × 4 = 80 km**