Task: Question Answering
Input (English): Problem: a and b together can complete work in 5 days . a alone starts working and leaves it after working for 3 days completing only half of the work . in how many days it can be completed if the remaining job is undertaken by b ? 
Options: a ) 4 , b ) 8 , c ) 15 , d ) 6 , e ) 7
Output (English): c