Task: Question Answering
Input (English): Problem: an engineer undertakes a project to build a road 10 km long in 150 days and employs 30 men for the purpose . after 50 days , he finds only 2 km of the road has been completed . find the ( approximate ) number of extra men he must employ to finish the work in time . 
Options: a ) 22 , b ) 30 , c ) 15 , d ) 18 , e ) 20
Output (English): b