20 men can do a work in 40 days . when should 20 men leave the work so that the entire work is completed in 40 days after they leave the work ?
"total work to be done = 20 * 40 = 800 let 20 men leave the work after ' p ' days , so that the remaining work is completed in 40 days after they leave the work . 40 p + ( 20 * 40 ) = 800 40 p = 0 = > p = 0 days answer : a"
divide(subtract(multiply(20, 40), multiply(40, 20)), 40)