if 36 men can do a piece of work in 25 hours , in how many hours will 10 men do it ?
explanation : let the required no of hours be x . then less men , more hours ( indirect proportion ) \ inline \ fn _ jvn \ therefore 10 : 36 : : 25 : x \ inline \ fn _ jvn \ leftrightarrow ( 10 x x ) = ( 36 x 25 ) \ inline \ fn _ jvn \ leftrightarrow \ inline \ fn _ jvn x = \ frac { 36 \ times 25 } { 10 } = 90 hence , 10 men can do it in 90 hours . answer : e ) 90
divide(multiply(36, 25), 10)