Task: Question Answering
Input (English): Problem: abel can complete a work in 10 days , ben in 12 days and carla in 16 days . all of them began the work together , but abel had to leave after 2 days and ben 4 days before the completion of the work . how long did the work last ? 
Options: a ) 6 , b ) 7 , c ) 7 2 / 3 , d ) 9 , e ) 10
Output (English): c