I2.4 In Figure 2, the angles of triangle $X Y Z$ satisfy $\angle Z \leq \angle Y \leq \angle X$ and $c \cdot \angle X=6 \cdot \angle Z$.
If the maximum possible value of $\angle Z$ is $d^{\circ}$, find the value of $d$.
$\begin{array}{l}2 \cdot \angle X=6 \cdot \angle Z \Rightarrow \angle X=3 \angle Z \\ \text { Let } \angle Z=z^{\circ}, \angle Y=y^{\circ}, \angle X=3 z^{\circ} \\ z+y+3 z=180(\angle \mathrm{s} \text { sum of } \triangle) \\ y=180-4 \mathrm{z} \\ \because \angle Z \leq \angle Y \leq \angle X \\ \therefore z \leq 180-4 z \leq 3 z \\ \frac{180}{7} \leq z \text { and } z \leq 36 \\ d=\text { the maximum possible value of } z=36\end{array}$