Task: Question Answering
Input (English): Problem: a worker can load one truck in 5 hours . a second worker can load the same truck in 8 hours . if both workers load one truck simultaneously while maintaining their constant rates , approximately how long , in hours , will it take them to fill one truck ? 
Options: a ) 2.5 , b ) 2.7 , c ) 2.9 , d ) 3.1 , e ) 3.3
Output (English): d