Problem in the Ask Marilyn column in the Parade insert in the Sunday paper on Nov 16, 2008:
Say that 70 cows take 24 days to eat all the grass in a pasture. That same pasture sustains 30 cows for 60 days. How many cows would take 96 days to eat all the grass? - A. Wright, Littleton, Colo.
 
 
Assume that all grass grows at the same rate and that all cows eat grass at the same rate

Hints: Construct equations with three elements,
   Amount of grass at first
   Grass's growth rate
   Cow's eat grass rate

Answer