Can someone work out 1&2 for me? I’m totally lost on what’s going on.

If i have 20$ and i gave 5$ away how much i got

Which function has the domain x> -11?

Aword processing program requires a 7- digit registration code made up of the digits 1,2,4,5,6,7 and 9 each number has to be used and no number can be used mor than once how many codes are possible