How many days will the woman be traveling?

W: When do you leave for holiday?
M: On the twentieth. We’re flying. The flight takes seven and a half hours.
W: And when are you back?
M：On the twenty-eighth. I will give you a ring when we’re back.

M: You’ll never guess what! I’ve won ＄50,000 on the lottery.
W: What... You lucky man! Well done! What are you going to do with it?
M: I think I’ll invest it for my old age.
W: That seems the best idea, I think.