15 laborers dig 40 acres for 40 days how much days wants 20 laborers for 60 acres?

If it takes 15 laborers 40 days to dig 40 acres...then they are digging 1 acre per day. And each laborer must dig 1/15 of an acre per day.

So 20 laborers would dig 20(1/15) acres = (4/3) acres per day. So 60/(4/3) = 45 days to dig 60 acres.