If the mailman delivered 6 letters on Monday, and another 4...

If the mailman delivered 6 letters on Monday, and another 4 letters on Tuesday, how many letters would you have?

a) ten letters

b) none, because someone is stealing them

c) none, because he delivered them to the wrong address

d) you don't know, because you've been at your F.I.F.O. job for the last week, and still have another 3 days to go before you get home.