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: if 3 men or 4 women can do a piece of work in 16 days , in how many days can 12 men and 8 women do the same piece of work ? 
Options: a ) 8 / 3 , b ) 6 , c ) 5 , d ) 4 , e ) 3
a

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
c

Problem: the length of a bridge in meters , which a train 100 - meters long and traveling at 45 km / hr can cross in 30 seconds is ? 
Options: a ) 225 , b ) 245 , c ) 275 , d ) 325 , e ) 375

c