A car can finish a certain journey in 10 hours at a speed of 42 kmph. In order to cover the same distance in 7 hours, the speed of the car (km/h) must be increased by:

The speed of a  boat in still water is 20 kmph and the rate of current is 4 kmph. The distance travelled by the boat downstream in 30 minute is

Travelling at 80km/hr, Praveen reaches his destination at a certain time. He covers 3/5th of his journey in 2/5th at the time. At what speed (in km/hr) should he travel to cover the remaining journey, so as to reach his destination on time? 

Speed of boat in downstream and upstream are 32km/hr and 23km/hr. Find the speed of current ?

A is twice fast as B and B is thrice as fast as C. The journey covered by C in 78 minutes then time taken by A to cover the same journey is-

Speed of boat in still water is 9 km/hr. Stream speed initially is 2 km/hr but it increases by 3 km/hr after every hour. Find the time after which boat will come back to the position where it started.(in hour)

Some students went on a field trip. At a speed of 6 km/h, they travelled by bikes for 2 hours; then at a speed of 2 km/h, they walked for another hour; then they took rest for an hour and had lunch for half an hour; then at a speed of 1 m/s, they walked for an hour to visit a garden; and finally at a speed 4 km/h, they returned home in 3 hours. Their average speed, in km/h, (rounded off to two places of decimal) is:

Two people A and B started their journey from P to Q and Q to P respectively. After crossing each other, A and B completed the remaining part of their journey in 3 hour 20 mins and 4 hours 48 mins respectively. If the speed of B is 80 km/hr, then find the speed of A in (km/ hr)?