A $1\mathrm{.}99-$kg particle has a velocity $(2\mathrm{.}013\mathrm{.}03)$ m$/$s$,$ and a $2\mathrm{.}96-$kg particle has a velocity $(0\mathrm{.}97+5\mathrm{.}94)$ m$/$s$.$

$($a$)$ Find the velocity of the center of mass.

$+$

m$/$s

$($b$)$ Find the total momentum of the system.

$+$

kg $$ m$/$s