In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Input: Consider Input: Problem: a tank can be filled by two pipes a and b in 60 minutes and 40 minutes respectively . how many minutes will it take to fill the tank from empty state if b is used for the first half time and then a and b fill it together for the other half . 
Options: a ) 15 mins , b ) 20 mins , c ) 25 mins , d ) 30 mins , e ) 35 mins

Output: d


Input: Consider Input: Problem: a river boat leaves silver town and travels upstream to gold town at an average speed of 6 kilometers per hour . it returns by the same route at an average speed of 5 kilometers per hour . what is the average speed for the round - trip in kilometers per hour ? 
Options: a ) 5.5 , b ) 7.1 , c ) 7.2 , d ) 7.0 , e ) 8.0

Output: a


Input: Consider Input: Problem: a man covers a distance on scooter . had he moved 3 kmph faster he would have taken 40 min less . if he had moved 2 kmph slower , he would have taken 40 min more . the distance is . 
Options: a ) 30 km , b ) 60 km , c ) 80 km , d ) 20 km , e ) 40 km


Output: e