Linear Programming Problem

Hi all,

I've been set a problem which, to me, appears to be in the form of a Critical Path Analysis problem, but we have been instructed to solve using Linear Programming. I have no problems solving the problem by means of CPA, but my LP knowledge is minimal and I don't understand how LP can be applied to the problem. Included below is the question - I'm not looking for someone to solve it for me, but any pointers on how to go about formulate as an LP problem would be greatly appreciated.

Quote:

A large construction project has been broken down into 6 main activities. The times to complete the activities and the necessary preceding activities are shown in the following table.

http://img513.imageshack.us/img513/6412/tablez.png
Formulate this solution as a Linear Programming problem, where the aim is to complete the project in the shortest possible time.

I have found the Critical Path (A-B-E-G) and minimum completion time (190 days), but I don't understand how this problem can be formulated for Linear Programming.

Thanks in advance,

ft_fan