in a garment industry , 12 men working 9 hours per day complete a piece of work in 10 days . to complete the same work in 12 days , working 15 hours a day , the number of men required is :
"explanation : let the required number of men be x . less days , more men ( indirect proportion ) more working hrs per day , less men ( indirect proportion ) days 8 : 10 working hrs 15 : 9 : : 12 : x = > 12 x 15 x x = 10 x 8 x 12 = > x = 10 x 9 x 12 / ( 12 x 15 ) = > x = 7 answer : d"
divide(divide(multiply(multiply(12, 9), 10), 15), 9)