Determine whether these genes are on the same chromosome or different?

I am not sure how to tell if genes are on the same chromosome or a different chromosome.  Please help explain this:

In Neurospora, a cross was made: ab x ++; and 100 asci were scored and placed into the seven possible classes as shown below:
    1    2    3    4    5    6    7
   ab    a+    ab    ab    ab    a+    a+
   ab    a+    a+    +b    ++    +b    +b
   ++    +b    ++    ++    ++    +b    ++
   ++    +b    +b    a+    ab    a+    ab
   69    0    10    17    1    1    2
a.   Determine whether these genes are on the same chromosome or different chromosomes.  Why?

b.   If linked on the same chromosome are they on the same or opposite arms. Why?


c.   Determine the map distance between genes (if linked), and between the genes and their respective centromeres. (Show your work, but answer the question with a map)