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: two trains 180 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 ) 10.7 , b ) 10.9 , c ) 10.24 , d ) 12.24 , e ) 18.8
[EX A]: d

[EX Q]: Problem: a train 140 m long running at 84 kmph crosses a platform in 16 sec . what is the length of the platform ? 
Options: a ) 287 , b ) 298 , c ) 233 , d ) 726 , e ) 267
[EX A]: c

[EX Q]: Problem: a and b can do a piece of work in 7 days , b and c in 8 days , c and a in 9 days . how long will c take to do it ? 
Options: a ) 14.1 days , b ) 18.8 days , c ) 21.4 days , d ) 24.3 days , e ) 26.5 days
[EX A]:
c