Genetics Hard problem!

[nnyeon145]

Based on the information in Experiment II, estimate the minimum genetic map distance between the two genetic loci. (Note: One genetic map unit (m.u.)
gives a recombinant frequency (RF) of 1 percent.)

I scanned the whole passage in the attachment.

Answer is 34 m.u.

This is what I did:
B+/ba x ba/ba (parental strands)

If there is no crossover, B+/ba (black), ba/ba (white)
If there is one crossover (between the sister chromatids), BA/ba (albino), b+/ba (brown)

So in the crossover, since crossover was done in between the two alleles, 100+34/200= 67amu. (wrong)

The back of the book started doing crossover between non sister chromatids. What about the crossover between sister chromatids? what does crossover between nonsister chromatids help with figurig out the location of the alleles?

[JackBean]

sister chromatids are identical, since they are product of DNA replication