A $0\mathrm{.}821$ kg particle has a velocity

$v_{0\mathrm{.}821kg}=$ahat$(i)+$bhat$(j),$

where $a=-79\mathrm{.}9\frac{m}{s}$ and $b=3\mathrm{.}92\frac{m}{s},$ and a $1\mathrm{.}94$ kg particle has a velocity

$v_{1\mathrm{.}94kg}=$chat$(i)+$dhat$(j)$

where $c=1\mathrm{.}33\frac{m}{s}$ and $d=2\mathrm{.}43\frac{m}{s}.$

Find the speed of the center of mass.

Answer in units of $\frac{m}{s}.$