What does an inversion do to gene mapping?

[cougar]

Hey guys just need a little assistance with some genetics homework. I am given a gene map and I am told that an inversion occurs between 3 of the 7 of the genes. It asks for the recombinant percentages which is simply just adding up the numbers between the genes. I just do not quite understand how to calculate the recombinant percentages when an inversion takes place. I attempted the problem and i just halved any number that was inside the inversion because i know that when an inversion takes place 2 chromosomes come out normal and two are affected by the inversion. I doubt this is right but any assistance would be great. If you need more information from the problem just let me know! Thanks everybody!