The tenor sax is in the key b flat and the alto sax is in the key e flat.
B flat.
B flat scale would be b flat, C, D, E flat, F, G, A, and High B flat
A B-Flat soprano sax is in the same key as a trumpet, clarinet, tenor sax, etc.. This is the most common soprano sax. If you were in band you'd probably be playing one of those parts as most band arrangements don't have a soprano sax part. An E-flat soprano sax is in the same key as an alto sax, or a bari sax. Sopranos in this key are less common & if you played this one in band they'd probably stick you with a alto sax part. My opinion is to get a b-flat as that is the most popular key for soprano & has more opportunities just in case the band actually does need a soprano, you'd be able to play the part.
A-flat Major scale
The subdominant in a scale is the 4th, which in the key of B-flat major is E-flat.
B-flat
G Flat, A Flat, B Flat, C Flat, D Flat, E Flat, F natural and back to G Flat.
B flat is in the d minor scale.
The mediant is the 3rd of the scale, so in B-flat it's D.
well the minor scale was unfortunait used to be b flat then it was changed to e flat.
B flat C D E flat F G A B flat