The frequency is related to the speed and wavelength by the formula:
[tex]f=\frac{v}{\lambda}[/tex]In this case, since we are talking of light, the speed is c which has a value of 3e8 m/s. Plugging this and the wavelength given we have:
[tex]\begin{gathered} f=\frac{3\times10^8}{569\times10^{-9}} \\ f=5.27\times10^{14} \end{gathered}[/tex]Therefore, the frequency is:
[tex]f=5.27\times10^{14}\text{ Hz}[/tex]