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 and b together can do a piece of work in 10 days . b alone can finish it in 20 days . in how many days can a alone finish the work ? 
Options: a ) 20 , b ) 10 , c ) 15 , d ) 5 , e ) 7
[A]: a


[Q]: Problem: two trains 120 m and 160 m long run at the speed of 60 km / hr and 40 km / hr respectively in opposite directions on parallel tracks . the time which they take to cross each other is ? 
Options: a ) 10.9 , b ) 10.7 , c ) 10.3 , d ) 10.08 , e ) 10.2
[A]: d


[Q]: Problem: a and b go around a circular track of length 300 m on a cycle at speeds of 34 kmph and 50 kmph . after how much time will they meet for the first time at the starting point ? 
Options: a ) 120 sec , b ) 60 sec , c ) 186 sec , d ) 167 sec , e ) 168 sec
[A]:
b