Collect all the "a"s together.
a + a = 2a
Collect the "b"s together
- b - 5b = - 6b
Collect the "c"s together
2c - c = c
Now put them all in one statement
2a - 6b + c <<<< answer
Note
I have answered this as though A and a are the same thing. If this is not correct, leave a note.