\documentclass[a4paper]{article}
\begin{document}
\begin{eqnarray*}
\mbox{(1)} \qquad T
 & = & \frac{c^{3} \hbar}{8 \pi G k} \frac{1}{M} \\
& = & \frac{c^{3} h}{16 \pi^{2} G k} \frac{1}{M} \\
& = & 1.227 \cdot 10^{23} \frac{1}{M} \\
& \propto & \frac{1}{M} \\
\end{eqnarray*}
\newpage
\begin{eqnarray*}
\mbox{(2)} \qquad P
 & = & \frac{2 \pi^{5} k^{4}}{15 c^{2} h^{3}} A T^{4} \\
& = & \sigma A T^{4} \\
& = & 5.67037 \cdot 10^{-8} \, A T^{4} \\
\end{eqnarray*}
\newpage
\begin{eqnarray*}
\mbox{(3)} \qquad T_{v}
 & = & \frac{5120 \pi G^{2}}{c^{4} \hbar} M^{3} \\
& = & \frac{10240 \pi^{2} G^{2}}{c^{4} h} M^{3} \\
& = & 8.411 \cdot 10^{-17} M^{3} \\
& \propto & M^{3} \\
\end{eqnarray*}
\end{document}
