There is a 1/3 chance that he will choose white bread, and a 1/8 chance that he will choose turkey as the meat. In order to figure out what the probability is that he will pick both of these, we multiply them together.
[tex] \frac{1}{3}* \frac{1}{8}= \frac{1}{24} [/tex]
So, the answer is 1/24 chance that he will make a white turkey sandwich.