four
The key of A-flat major contains four flats: B, E, A, and D.
The key of E-flat major contains three flats: Bb, Eb, and Ab.
7
five rods.
10
40
There are 30 dozen in a case, and 15 dozen in a box.
Depends on species.
There can be a total of seven flats (or sharps) in a key signature.
Cb major has all 7 flats
6
six
Two flats, B flat and E flat
3
six
Three