In fruit flies, eye color is a sex-linked trait determined by a single
gene with two alleles. Red color is dominant to white eye color. Body
color  is an autosomal trait determined by a single gene with two
alleles, where brown is dominant to yellow.
if a homozygous red eyed female, homozygous of yellow body color is
crossed to a white-eyed male homozygous for brown body color, what
proportion of the second-generation male offsping will have red eyes
and brown bodies?

OK, for the sex-linked eye-color trait, the alleles are:
XW - dominant red color
Xw - recessive white eye color
Y - male's Y chromosome doesn't contain eye-color gene at all

for the other trait, there are just two alleles:
B - brown body color
b - yellow body color

so if a homozygous red eyed female, homozygous of yellow body color is
crossed to a white-eyed male homozygous for brown body color, we're
combining XWXWbb with XwYBB, so the offspring will all have Bb for
body color genes, and will thus all be brown, and their sex genes will
be half XWXw and half XWY, so they will be half male, half female, and
all red-eyed.

in the second generation, we'll be mating XWXwBb females with XWYBb
males.

considering only body color for a moment, mating Bb with Bb will
produce the normal equal mixture of BB, Bb, bB, and bb, so
three-fourths of the offspring will display the dominant brown body
phenotype.

as far as the sex-linked eye color trait, the male offspring will all
get a Y chromosome from their fathers, and either an XW or Xw from
their mothers, so half of them will be XWY and red-eyed, and the other
half XwY and white-eyed.

so, combining the two traits, we'll have:

1/8th  XwYbb             white-eyed, yellow-bodied
1/8th  XWYbb             red-eyed, yellow-bodied
3/8ths XwY(BB, Bb, bB)   white-eyed, brown-bodied
3/8ths XWY(BB, Bb, bB)   red-eyed, brown-bodied.

so, in particular, three eighths of the second-generation males will
have red eyes and brown bodies.

one web page I checked to make sure I wasn't forgetting the details
was http://library.thinkquest.org/18258/noframes/morgan2.htm?tqskip1=1&tqtime=0408,
which I found by searching for "fruit flies sex linked eye color".

again, if you have further questions, or my explanation isn't clear,
please ask for a clarification.

Thanks again,
David