30 men can do a work in 40 days. When should 10 men leave the work so that the entire work is completed in 40 days after they leave the work? Pick one
A) 87 days B) 10 days C) 55 days D) 44 days E) 20 days

Rationale: "total work to be done = 30 * 40 = 1200 let 10 men leave the work after ' p ' days , so that the remaining work is completed in 40 days after they leave the work . 40 p + ( 10 * 40 ) = 1200 40 p = 800 = > p = 20 days answer : e"
Answer: E