Answer
$v=30\frac{m}{s}$ in the +x direction
Work Step by Step
The given equation is $y=(2.0mm)sin[(20m^{-1})x]-(600s^{-1})t]$
By comparing the given equation with $y_(x,t)=y_m sin(kx-\omega t)$ we obtain:
$k=20m^{-1}$
We know that
$v=\frac{\omega}{k}$
We plug in the known values to obtain:
$v=\frac{600}{20}=30\frac{m}{s}$ in the +x direction
