A swimmer can swim 68 km downstream and 45 km upstream in 9 hours and he will take 2 hours more to swim 51 km downstream and 72 km upstream. Find the speed of the swimmer in still water.

Speed of a boat in still water is 12 kmph and that of the current is 3 kmph. A man row a boat upstream up to 135 km and return downstream to the starting point. Find the total time taken for the entire journey in hours.

A boat goes from A to B in upstream and come back from B to A downstream taking a total time of 3.5 hours. If the speed of boat in still water is 7 km/hr and the speed of stream is 5 km/hr. Find the distance between A and B. 

A person rows a distance of $$ {3{3\over4}{ \ km}}$$ upstream in $$ {1{1\over 2}{\ hours}}$$ and a distance of 13 km downstream in 2 hours. How much time ( in hours) will the person take to row a distance of 90 km in still water?

The ratio of speed of boat in still water to speed of stream is 8 : 1. It takes 4 hours by boat to cover 54 km in downstream & 42 km in upstream. Find the downstream speed of boat.

Speed of boat in upstream is 11km/hr and downstream is 23 km/hr find the speed of boat in still water?

A man can row 30 km upstream and 44 km downstream in 10 hours. Also, he can row 40 km upstream and 55 km downstream in 13 hours. The rate of the current is – 

Two boats are traveling with speeds of 36 km/hr and 54 km/hr respectively towards each other. What is the distance (in meters) between the two boats one second before they collide?