LaTeX Forum

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\begin{document}
\begin{subequations}\label{eq:1}
\begin{minipage}{0.45\textwidth}
\begin{align}
\label{eq:1a}
X&=\frac{K_2}{K_2+K_1}
\end{align}
\end{minipage}
\begin{minipage}{0.45\textwidth}
\begin{align}
\label{eq:1b}
X&=\frac{K_1}{K_2+K_1}
\end{align}
\end{minipage}
\end{subequations}
\begin{subequations}\label{eq:2}
\begin{align}
\label{eq:2a}
\frac{\partial X}{\partial t}&=K\cdot\Delta X-\left( K_1+K_2 \right)X+K_2\cdot X+XK_1\\
\label{eq:2b}
\frac{\partial X}{\partial t}&=K_1X-\left( K_2+K_1 \right)X+XK_1
\end{align}
\end{subequations}
text in the description for further information....blablabla

\begin{subequations}\label{eq:3ab}
\begin{minipage}{0.45\textwidth}
\begin{align}
X1&=X-K\nonumber
\end{align}
\end{minipage}
\begin{minipage}{0.45\textwidth}
\begin{align}
X1&=X-K\nonumber
\text{\qquad numbering (3a,b) would be nice}
\end{align}
\end{minipage}
\end{subequations}
\begin{align}
\label{eq:4}
K_1X&=XK
\end{align}
\begin{subequations}\label{eq:5}
\begin{align}
\label{eq:5a}
\frac{\partial X1}{\partial t}&=K\cdot\Delta X1-\left( K_1+K_2\right)X1+K_2\cdot X1\\
\label{eq:5b}
\frac{\partial X1}{\partial t}&=K_1X1-\left( K_2+K_1 \right)X1
\end{align}
\end{subequations}
\begin{align}
\label{eq:6a,b}
X=K_1X=K2X+KX1
\text{\qquad numbering (6a,b) would be nice}
\end{align}
\end{document}