Two mobiles (RO)

The rectilinear movement of two mobiles are described by the motions laws x1=3t and  x2=10–t where x is expressed in meters and t in seconds. The mobiles start at the same time t0=0 s. Find out: a.       The graphical representation of the coordinates of the movable laws of the mobile; b.      The time and the place where the two mobiles meet.