Uniform electric and magnetic fields with strength E and induction B respectively are directed along the g

Question:

Uniform electric and magnetic fields with strength E and induction B respectively are directed along the g axis (Fig. 3.101). A particle with specific charge q/m leaves the origin O in the direction of the x axis with an initial non-relativistic velocity re. Find:
(a) The coordinate yn of the particle when it crosses the g axis for the nth time;
(b) The angle a between the particle's velocity vector and the g axis at that moment.