Two cars collide at an intersection. Car A$,$ with a mass of $1900$ kg$,$ is going from west to east, while car B$,$ of mass $1400$ kg$,$ is going from north to south at $17$ m$/$s$.$ As a result of this collision, the two cars become enmeshed and move as one afterward. In your role as an expert witness, you inspect the scene and determine that, after the collision, the enmeshed cars moved at an angle of $65\circ$ south of east from the point of impact. 

a$)$How fast were the enmeshed cars moving just after the collision? 

b$)$How fast was car A going just before the collision?