Help needed setting up an inequalities word problem

I can't seem to figure out how to set this problem up. I can probably solve it, but I can't get anywhere unless I can set it up. The question is as follows...

Suppose a TV dealer has stores in Annapolis and Rockville, and warehouses in College Park and Baltimore. The cost of shipping sets from College Park to Annapolis is $6 per set; from College Park to Rockville, $3; from Baltimore to Annapolis, $9; and from Baltimore to Rockville, $5. Suppose Annapolis store orders 25 sets and the Rockville store orders 30. Also, suppose that the College Park warehouse has 45 sets in stock, and that the Baltimore warehouse has 40 sets. What is the most economical way to ship the requested TV sets to the two stores, and what is the minimum cost?

http://i14.photobucket.com/albums/a3...athProblem.jpg

Let X1 = the number of sets shipped from College Park to Rockville.

Let X2 = the number of sets shipped from College Park to Annapolis.

I know it's going to be an inequality set with mixed constraints because I have to solve using the Big M method. I appreciate any help that can be given. Thanks in advance (Smile)