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: two trains of equal lengths take 10 sec and 8 sec respectively to cross a telegraph post . if the length of each train be 120 m , in what time will they cross other travelling in opposite direction ? 
Options: a ) 22 , b ) 12 , c ) 9 , d ) 99 , e ) 21
c

Problem: a and b can together finish a work in 40 days . they worked together for 10 days and then b left . after another 6 days , a finished the remaining work . in how many days a alone can finish the job ? 
Options: a ) 10 , b ) 25 , c ) 60 , d ) 8 , e ) 20

d