8 children and 10 men complete a certain piece of work in 9 days.Each child takes twice the time taken by a man to finish the work.In how many days will 12 men finish the same work?
Here's how I'd do. Since each child takes twice the time than a man, we can consider that 2 children are worth 1 man.
Hence 8 children worth 4 men. And thus 14 men would complete the piece of work in 9 days.
14 men -> 9 days
12 men -> ? days
That's a cross product