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'.

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

Problem: some persons can do a piece of work in 12 days . two times the number of these people will do half of that work in ?
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 8
a

Problem: a , b and c can do a piece of work in 24 days , 30 days and 60 days respectively . they began the work together but c left 4 days before the completion of the work . in how many days was the work completed ?
Options: a ) 10 days , b ) 11 days , c ) 13 days , d ) 21 days , e ) 31 days
b