In a $\Delta PQR$ if $3\sin P+4\cos Q=6.4\sin Q+3\cos P=1$ then the angle $R$ is equal to

Question

$\begin{array}{1 1}(a)\;\large\frac{5\pi}{6}&(b)\;\large\frac{\pi}{6}\\(c)\;\large\frac{\pi}{4}&(d)\;\large\frac{3\pi}{4}\end{array}$