Two satellites P and Q are moving in different circular orbits...

Acceleration due to gravity at any height from the Earth's surface is given by, $g = \dfrac{GM}{{r}^{2}}$, where $r =$distance from the centre of the Earth.

Now, we can write

$\dfrac{{g}_{P}}{{g}_{Q}} = \dfrac{\dfrac{GM}{{\left({r}_{P}\right)}^{2}}}{\dfrac{GM}{{\left({r}_{Q}\right)}^{2}}} ⇒ \dfrac{36}{25} = {\left(\dfrac{{r}_{Q}}{{r}_{P}}\right)}^{2} ⇒ \dfrac{{r}_{Q}}{{r}_{P}} = \dfrac{6}{5} ⇒ {r}_{Q} = \dfrac{6}{5} \times \left(R + \dfrac{R}{3}\right) ⇒ R + {h}_{Q} = \dfrac{8}{5}R ⇒ {h}_{Q} = \dfrac{3}{5}R$