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'.

Q: Problem: a man can row upstream at 5 kmph and downstream at 25 kmph , and then find the speed of the man in still water ? 
Options: a ) 15 , b ) 77 , c ) 30 , d ) 88 , e ) 34

A: a
****
Q: Problem: john traveled 80 % of the way from yellow - town to green - fields by train at an average speed of 80 miles per hour . the rest of the way john traveled by car at an average speed of v miles per hour . if the average speed for the entire trip was 60 miles per hour , what is v in miles per hour ? 
Options: a ) 30 , b ) 40 , c ) 50 , d ) 55 , e ) 70

A: a
****
Q: Problem: a and b together can do a piece of work in 8 days . if a alone can do the same work in 12 days , then b alone can do the same work in ? 
Options: a ) 49 , b ) 99 , c ) 24 , d ) 88 , e ) 21

A:
c
****