Alternative Equation Formats

$$\begin{array}{rcl}\underset{x=s_0}{\overset{x=u}{\sum <!--\; \sum \; -->}}{C}_x{\mathrm{\varphi <!--\; \varphi \; -->}}_1^x/\underset{x=l}{\overset{x=u}{\sum <!--\; \sum \; -->}}{C}_x{\mathrm{\varphi <!--\; \varphi \; -->}}_1^x& =& \mathrm{\alpha <!--\; \alpha \; -->}/2\\ \underset{x=l}{\overset{x=s_0}{\sum <!--\; \sum \; -->}}{C}_x{\mathrm{\varphi <!--\; \varphi \; -->}}_2^x/\underset{x=l}{\overset{x=u}{\sum <!--\; \sum \; -->}}{C}_x{\mathrm{\varphi <!--\; \varphi \; -->}}_2^x& =& \mathrm{\alpha <!--\; \alpha \; -->}/2\end{array}$$

$$\begin{array}{rcl}\underset{x=s_0}{\overset{x=u}{\sum <!--\; \sum \; -->}}{C}_x{\mathrm{\varphi <!--\; \varphi \; -->}}_1^x/\underset{x=l}{\overset{x=u}{\sum <!--\; \sum \; -->}}{C}_x{\mathrm{\varphi <!--\; \varphi \; -->}}_1^x& =& \mathrm{\alpha <!--\; \alpha \; -->}/2\\ \underset{x=l}{\overset{x=s_0}{\sum <!--\; \sum \; -->}}{C}_x{\mathrm{\varphi <!--\; \varphi \; -->}}_2^x/\underset{x=l}{\overset{x=u}{\sum <!--\; \sum \; -->}}{C}_x{\mathrm{\varphi <!--\; \varphi \; -->}}_2^x& =& \mathrm{\alpha <!--\; \alpha \; -->}/2\end{array}$$

\begin{eqnarray*} \sum _{x~ =~ s_0}^{x~ =~ u} ~ C_ x ~ \phi _1^{~ x} ~ / ~ \sum _{x~ =~ l}^{x~ =~ u} ~ C_ x ~ \phi _1^{~ x} & = & \alpha / 2 \\[0.10in] \sum _{x~ =~ l}^{x~ =~ s_0} ~ C_ x ~ \phi _2^{~ x} ~ / ~ \sum _{x~ =~ l}^{x~ =~ u} ~ C_ x ~ \phi _2^{~ x} & = & \alpha / 2 \end{eqnarray*}