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: calculate the speed of a boat in still water ( in km / hr ) if in one hour , the boat goes 10 km / hr downstream and 4 km / hr upstream . 
Options: a ) 7 kmph , b ) 8 kmph , c ) 9 kmph , d ) 7 kmph , e ) 6 kmph
[EX A]: a

[EX Q]: Problem: a is twice as good a workman as b and together they complete a work in 12 days . in how many days a alone can do the work ? 
Options: a ) 32 , b ) 33 , c ) 34 , d ) 35 , e ) 36
[EX A]: e

[EX Q]: Problem: a train travels from albany to syracuse , a distance of 120 miles , at the average rate of 50 miles per hour . the train then travels back to albany from syracuse . the total travelling time of the train is 5 hours and 30 minutes . what was the average rate of speed of the train on the return trip to albany ? 
Options: a ) 31 , b ) 38.7 , c ) 35 , d ) 36 , e ) 39
[EX A]:
b