Transposing music means to move from one key to another. This can be useful in many respects:
https://www.youtube.com/watch?v=VEJFuWgkGkY
A |
B |
A |
A |
B |
A |
E♭ major TONIC key |
B♭ major DOMINANT |
A |
C minor RELATIVE MINOR key |
A |
A |
The following piece is in the key of D major. So is section A every time. Can you work out the key for sections B and C? Look at the accidentals. As in the case of Mozart’s Rondo, why not begin by looking for the relative keys such as the dominant and relative minor first?