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: if 42 men do a work in 25 days , in how many days will 50 men do it ?
Options: a ) 23 , b ) 22 , c ) 19 , d ) 20 , e ) 21
[EX A]: e

[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: the hiker walking at a constant rate of 4 miles per hour is passed by a cyclist traveling in the same direction along the same path at 10 miles per hour . the cyclist stops to wait for the hiker 5 minutes after passing her , while the hiker continues to walk at her constant rate , how many minutes must the cyclist wait until the hiker catches up ?
Options: a ) 10 , b ) 15 , c ) 20 , d ) 15 / 2 , e ) 24
[EX A]:
d