if 36 men can do a piece of work in 20 hours , in how mwny hours will 15 men do it ?
"explanation : let the required no of hours be x . then less men , more hours ( indirect proportion ) \ inline \ fn _ jvn \ therefore 15 : 36 : : 20 : x \ inline \ fn _ jvn \ leftrightarrow ( 15 x x ) = ( 36 x 20 ) \ inline \ fn _ jvn \ leftrightarrow \ inline \ fn _ jvn x = \ frac { 36 \ times 20 } { 15 } = 48 hence , 15 men can do it in 48 hours . answer : b ) 48"
divide(multiply(36, 20), 15)