Correct Answer - Option 2 : 18

**Given**

The car can finish a certain journey in 10 hours at the speed of 42 kmph

**Formula used**

Speed = Distance/Time

**Calculation**

Total distance covered by car = 10 × 42 = 420 km

Next, the distance should be covered in 7 hours

⇒ New speed = 420/7 = 60 km/hr

**∴ Speed of car must be increase by (60 - 42) = 18 km/hr**