I need help with this question The ability to curl your tong

I need help with this question.

The ability to curl your tongue up on the sides (T, tongue rolling) is dominant to not being able to roll your tongue (t, non-rolling tongue). A woman who can roll her tongue marries a man who cannot. Their first child has his father\'s phenotype. What are the genotypes of the mother? Tt tt tR TT

Answer: Tt