The equation of wave is given by

$\mathrm{Y}=10^{-2} \sin 2 \pi(160 t-0.5 x+\pi / 4)$

where $x$ and $Y$ are in $\mathrm{m}$ and $\mathrm{t}$ in $s$. The speed of the wave is ________ $\mathrm{km} ~\mathrm{h}^{-1}$.