|D|[thermodynamics] For an ideal gas, the $P V T$ equations are given by
$$
P_{1}\left(V_{1}\right)^{k}=P_{2}\left(V_{2}\right)^{k} \text { and } \frac{P_{1} V_{1}}{T_{1}}=\frac{P_{2} V_{2}}{T_{2}}
$$
where $P, V, T$ are pressure, volume, temperature respectively and $k$ is a constant. Show that
$\mathbf{i} \frac{T_{2}}{T_{1}}=\left(\frac{V_{1}}{V_{2}}\right)^{k-1}$
ii $\frac{T_{1}}{T_{2}}=\left(\frac{V_{2}}{V_{1}}\right)^{k-1}$