The reaction,

$3{\mathrm{I}}^{-}\left(\mathrm{aq}\right)+{\mathrm{S}}_2{{\mathrm{O}}_8}^{2-}\left(\mathrm{aq}\right)⟶{\mathrm{I}}_3-\left(\mathrm{aq}\right)+2{{\mathrm{SO}}_4}^{2-}\left(\mathrm{aq}\right)$

yields the kinetic data in the table.

${\left[{\mathbf{I}}^{-}\right]}_0\left({\mathrm{molL}}^{-1}\right)$	${\left[{\mathrm{S}}_2{{\mathrm{O}}_8}^{2-}\right]}_0\left(\mathrm{mol} \mathrm{L}\right)$	Relative Rate
0.001	0.001	1
0.002	0.001	2
0.002	0.002	4

What is the rate equation?