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: the length of the bridge , which a train 130 meters long and travelling at 45 km / hr can cross in 30 seconds , is ? 
Options: a ) 288 , b ) 266 , c ) 245 , d ) 277 , e ) 211
[EX A]: c

[EX Q]: Problem: two trains of length 100 meters and 200 meters are 840 meters apart . they are moving towards each other on parallel tracks , at speeds of 54 km / h and 72 km / h . after how many seconds will the trains meet ? 
Options: a ) 20 , b ) 22 , c ) 24 , d ) 26 , e ) 28
[EX A]: c

[EX Q]: Problem: machine a and machine b process the same work at different rates . machine c processes work as fast as machines a and b combined . machine d processes work 3 times as fast as machine c ; machine d ’ s work rate is also exactly 4 times machine b ’ s rate . assume all 4 machines work at fixed unchanging rates . if machine a works alone on a job , it takes 7 hours . if all 4 machines work together on the same job simultaneously , how many minutes will it take all of them to complete it ? 
Options: a ) 8 , b ) 21 , c ) 24 , d ) 27 , e ) 30
[EX A]:
b