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: a prison of 10,000 inmates has enough food to feed them all for 50 days . after 10 days some of the inmates leave and the food is now enough for the same period of 50 days as before . how many of them left ?
Options: a ) 3,000 , b ) 2,200 , c ) 2,000 , d ) 1,000 , e ) 200
[EX A]: c

[EX Q]: Problem: walking with 4 / 5 of my usual speed , i arrive at the bus stop 7 minutes later than normal . how many minutes does it take to walk to the bus stop at my usual speed ?
Options: a ) 12 , b ) 16 , c ) 20 , d ) 24 , e ) 28
[EX A]: e

[EX Q]: Problem: two trains are running in opposite directions in the same speed . the length of each train is 120 meter . if they cross each other in 12 seconds , the speed of each train ( in km / hr ) is
Options: a ) 30 km / hr , b ) 36 km / hr , c ) 80 km / hr , d ) 90 km / hr , e ) none of these
[EX A]:
b