Correct Answer - Option 3 : 42 km/h

**Given:**

Ratio of speed of bus = 7 ∶ 9

Distance covered by 2nd bus = 378 km

Time taken = 7 hrs

**Formula used:**

Speed = Distance/Time

**Calculation:**

Let the speed of buses = 7a and 9a

∵ Speed of 2nd bus = 378/7

= 54 km/h

∴ 9a = 54 km/h

⇒ a = 54/9 = 6 km/h

∴ Speed of the 1st bus = 7a

= (7 × 6) km/h

= 42 km/h