Waves

Two waves $y_1=\mathrm{A} \cos (0.5 \pi x-100 \pi t)$ and $y_2=\mathrm{A} \cos (0.467 \pi x-92 \pi t)$ are travelling in a pipe placed along $x$-axis.

Find the number of times $y_1+y_2=0$ at $x=0$ in $1 s$.