The basic relationship between frequency of an electromagnetic wave and wavelength of the wave is
[tex]c = \lambda f [/tex]
where [tex]c=3 \cdot 10^8 m/s[/tex] is the speed of light.
Manipulating the equation, we can rewrite it as
[tex]\lambda = \frac{c}{f}[/tex]
The frequency of the wave in our problem is
[tex]9.76 GHz = 9.76 \cdot 10^9 Hz[/tex]
so if we use the previous formula, we find the correspondant wavelength:
[tex]\lambda = \frac{3 \cdot 10^8 m/s}{9.76 \cdot 10^9 Hz} =0.031 m[/tex]