Answer
$f=7.50\times 10^{-14}Hz$
Work Step by Step
Recall that the equation for a wave function is $$y(x,t)=Asin(kx-\omega t)$$ Using the equation $k=\frac{2\pi}{\lambda}$, it can be concluded that $\lambda=\frac{2\pi}{k}$. Also, using the fact that an electromagnetic wave follows the equation $c=f \lambda$, substitution yields $$c=\frac{2\pi f}{k}$$ Solving for $f$ yields $$f=\frac{ck}{2\pi}$$ Substituting values of $k=1.57 \times 10^7 m^{-1}$ and $c=3.00\times 10^8m/s$ yields $$f=\frac{(3.00\times 10^8m/s)(1.57\times 10^7 m^{-1})}{2\pi}$$ $$f=7.50\times 10^{14} Hz$$
