Black fur is dominant to gray fur. if a gray mouse and a purebred black mouse are crossed, what are the possible genotypes of the offspring?

Seventy five percent chance it'll be black and twenty five percent it'll be gray

You did not show us the image of the burger, but i shall try to answer as best i can.  when purchasing food, always consider the ingredients as well as the person who prepared it. consider if they were hygienic people or not, in case the burger was infected with bacteria. no mortal should place an infected burger into their mouth.   

Yes, this is very true. specifically causing damage in the  dentrite.