confused?

Thank you, I know that the answer is not provided, but I am looking for some type of explanation. I know the basic process, but like I said, no one can seem to figure it out in my class.

I am currently in a genetics college course and we received an extra credit restriction mapping problem that no one seems to really understand how to do, and unfortunately the teacher hasn't been much help. If anyone could explain how to do it, I would greatly appreciate it!! Problem: A piece of DNA 5,000 base pairs long is digested w/ restriction enzymes A and B, singly and together. The DNA fragments produced are separated by DNA electrophoresis and their sizes are calculated with the following results (in base pairs): Digestion with--- A = 2,100, 1,400, 1,000, and 500 B=2,500, 1,300, and 1,200 A&B=1,900, 1,000, 800, 600, 500, 200 Each A fragment is extracted from the gel and digested with enzyme B and each B fragment is extracted and digested with enzyme A. The sizes of the resulting DNA fragment are determined by gel electrophoresis with the following results: Fragment A digested with enzyme B -2,100-->1,900 & 200 -1,400-->800 & 600 -1,000-->1,000 -500-->500 Fragement B digested with enzyme A -2,100-->1,900 & 600 -1,300-->800 &500 -1,200-->1,000 & 200 Construct a restriction map of the 5,000 bp DNA fragment. Merged post follows: Consecutive posts mergedI forgot to say that this problem is due tomorrow. So any help would be greatly appreciated!!