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'.

Ex 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

Ex Output:
d


Ex Input:
Problem: walking with 4 / 5 of my usual speed , i arrive at the bus stop 7 minutes later than normal . how many minutes does it take to walk to the bus stop at my usual speed ? 
Options: a ) 12 , b ) 16 , c ) 20 , d ) 24 , e ) 28

Ex Output:
e


Ex Input:
Problem: bexy walks 5 miles from point a to point b in one hour , then bicycles back to point a along the same route at 15 miles per hour . ben makes the same round trip , but does so at half of bexy ’ s average speed . how many minutes does ben spend on his round trip ? 
Options: a ) 40 , b ) 80 , c ) 120 , d ) 160 , e ) 180

Ex Output:

d