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: an employer pays rs . 20 for each day a worker works and for felts rs . 3 for each day is ideal at the end of sixty days a worker gets rs . 280 . for how many days did the worker remain ideal ? 
Options: a ) 10 , b ) 40 , c ) 30 , d ) 20 , e ) 50

Ex Output:
b


Ex Input:
Problem: walking with 4 / 5 of my usual speed , i miss the bus by 7 minutes . what is my usual time ? 
Options: a ) 16 min , b ) 26 min , c ) 28 min , d ) 20 min , e ) 12 min

Ex Output:

c