The distance between two towns is covered in 7 hours at a speed of 50 km/h. By how much should the speed (in km/h) be increased so that 2 hours of travelling time will be saved?

70 20 40 30

20

Distance = Speed × Time Distance = 50 × 7 = 350 km To cover distance in 2 hour less . i.e. 5 hours Speed = \(\frac{350}{5}\) = 70  km/h Increment in speed = 70 - 50 =  20 km/h