Two satellites S _ 1 and S _ 2 are revolving in circular orbits...

Orbital velocity of a satellite in circular motion around a planet,

${v}_{o} = \sqrt{\dfrac{GM}{R}} ∝ \dfrac{1}{\sqrt{R}}$

Now, $\dfrac{{v}_{1}}{{v}_{2}} = \sqrt{\dfrac{{R}_{2}}{{R}_{1}}} = \sqrt{\dfrac{800}{3200}} = \dfrac{1}{2}$

Hence, the value of $x = 2$.