Sphere $A$ and Sphere $B$ are metal spheres of identical size and shape. They are set on insulating stands and each has a different initial charge. Spheres $A$ and $B$ come into contact. A spark between the spheres indicates that a charge is transferred. After contact, each sphere has a charge of negative 5 micro-coulombs.
If the charge on Sphere $A$ was positive 22 micro-coulombs before contact, what was the charge on Sphere $B$ before contact?