I was unable to find it :/, I think you want to know the Sped on the X axis, with the minus if it goes to the left, we can recreate the expression should be okay too:
Sprite.Bullet.Speed and Sprite.Bullet.AngleOfMotion will help us
your VectorX is equal to:
(Sprite.Bullet.Speed * cos(Sprite.Bullet.AngleOfMotion))
and also VectorY is equal to:
(Sprite.Bullet.Speed * sin(Sprite.Bullet.AngleOfMotion))
Sprite is the name of your sprite
Tell me if I am wrong