Task: Question Answering
Input (English): Problem: excluding stoppages , the speed of a bus is 90 km / hr and including stoppages , it is 84 km / hr . for how many minutes does the bus stop per hour ? 
Options: a ) 18 min , b ) 4 min , c ) 8 min , d ) 6 min , e ) 5 min
Output (English): b