On a certain pasture grass grows at a even rate. It is known that 40 cows can graze on it for 40 days before the grass is exhausted, but 30 cows can graze there as long as 60 days.

How many days would pasture last if 20 cows were to graze on it ?

(In reply to solution by Charlie)

That line
1=(20/1200)d

should of course be
1=(20/1200 - 1/120)d

Posted by Charlie on 2003-08-13 14:48:04