Complementation problem: possible region of deletion place the mutation on the thick line which ...

I need help with part B of this problem, I've asked Genetics tutors, other professors and even went on chegg to use the expert Q&A --  I've done part A and I know that 3 complements 1, 2 and 6 are unable to complement and 3,4,5 and 1,2 6 have similar mutations

but I have no idea if I am right?
my genetics professor says that if I look at row 4 and I have to see what 4x5 mating results in? does that mean the chart where I added the + and - are incorrect?

for part b the hint is that if a mutation falls in a deletion region, no complementation is possible so there will be a "-" in the table -- that tells me the location of the mutation along the chromosome.

Can someone please help me with this problem? I've spent 3 days and still no progress. Appreciate your help every much!