The relationship between frequency f, speed of light c and wavelength [tex]\lambda[/tex] is
[tex]c= \lambda f[/tex]
In our problem, the wavelength is [tex]\lambda=103 nm = 103 \cdot 10^{-9} m[/tex] while the speed of light is [tex]c=3 \cdot 10^8 m/s[/tex], so the frequency of the light is
[tex]f= \frac{c}{\lambda}= \frac{3 \cdot 10^8 m/s}{103 \cdot 10^{-9} m}=2.9 \cdot 10^{15}Hz [/tex]
