In Drosophila, the gene spineless maps to the third
chromosome, while brown and purple are both on
the second chromosome 6cM apart. Consider the alleles ss,
b and p with recessive phenotypes
–spineless bristles (ss), brown body (b)
and purple eyes (p).

What frequencies would you expect for the various phenotypes
amongst the offspring of the testcross (note that comma
separates alleles on the same chromosome, semicolon separates
different chromosomes):

+, + / b, p ; +/ss     
x     b, p / b, p ; ss/ss (testcross)