Starting from the origin at time $t=0$, with initial velocity $5\hat j\,\,\,{\rm{m}}{{\rm{s}}^{ - 1}}\,$ a particle moves in the xy- plane with a constant acceleration of $(10\hat i + 4\hat j)\,\,{\rm{m}}{{\rm{s}}^{ - 2}}.\,$ At time $t,$ its coordinates are $(20\,\,{\rm{m,}}\,\,{{\rm{y}}_0}\,{\rm{m}}).$ The values of $t{\rm{ }}\,\,\,{\rm{and}}\,\,\,{\rm{ }}{y