G2.1 In Figure $1, P R S$ is a straight line, $P Q=P R=Q S$ and $\angle Q P R=30^{\circ}$. If $\angle R Q S=w^{\circ}$, find the value of $w$.
$\begin{array}{l}\angle Q P R=\angle Q S P=30^{\circ}(\text { base } \angle \mathrm{s} \text { isos. } \triangle) \\ \angle P Q S=120^{\circ}(\angle \mathrm{s} \mathrm{sum} \text { of } \triangle) \\ \angle P Q R=\angle P R Q=\left(180^{\circ}-30^{\circ}\right) \div 2=75^{\circ}(\angle \mathrm{s} \text { sum of isos. } \triangle) \\ \angle R Q S=120^{\circ}-75^{\circ}=45^{\circ} \Rightarrow w=45\end{array}$