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 Q]: Problem: a boat takes 19 hours for travelling downstream fro poin a to point b and coming back to a point c midway between a and b . if the velocity of the stream is 4 kmph and the speed of the boat in still water is 14 kmph , what is the distance between a and b ? 
Options: a ) 180 km , b ) 190 km , c ) 220 km , d ) 230 km , e ) none
[EX A]: a

[EX Q]: Problem: an seller earns an income of re 1 on the first day of his business . on every subsequent day , he earns an income which is just thrice of that made on the previous day . on the 20 th day of business , he earns an income of : 
Options: a ) 29 , b ) 57 , c ) 35 , d ) 20 , e ) 30
[EX A]: b

[EX Q]: Problem: a can do a work in 12 days . b can do the same work in 24 days . if both a & b are working together in how many days they will finish the work ? 
Options: a ) 3 , b ) 5 , c ) 8 , d ) 2 , e ) 6
[EX A]:
c