A 6.45 $\mu C$ particle moves through a region of space where an electric field of magnitude 1270 N/C points in the positive $x$ direction, and a magnetic field of magnitude 1.18 T points in the positive $z$ direction. If the net force acting on the particle is 6.11E-3 N in the positive $x$ direction, calculate the magnitude of the particle's velocity. Assume the particle's velocity is in the $x$-$y$ plane.