Task: Question Answering
Input (English): Problem: a and b start walking towards each other at 6 pm at speed of 6 kmph and 4 kmph . they were initially 50 km apart . at what time do they meet ? 
Options: a ) 8 pm , b ) 6 pm , c ) 11 pm , d ) 10 pm , e ) 5 pm
Output (English): c