(d) Compare the given equation with
$y = a\sin{(\omega t + kx) \Rightarrow \omega = 2\pi n = 100 \Rightarrow n = \frac{50}{\pi}Hz}$
$k = \frac{2\pi}{\lambda} = 1 \Rightarrow \lambda = 2\pi$and $v = \omega/k = 100\ m/s$
Since $' + '$ is given between $t$ terms and $x$ term, so wave is travelling in negatie $x$-direction