# Equation numbering and combined blocks (aligned)

I have 2 sets à 2 equations which I want to print side by side with a centered arrow in between, and equation numbers (1a), (1b) on the right. But I cannot get the numbering right. The closest I was able to get is with

\begin{subequations}
\begin{align}
\begin{aligned}
a &= b \\ c &=d
\end{aligned}
&& \implies &&
\begin{aligned}
x &=y \\ z &= w
\end{aligned}
\end{align}
\end{subequations}


Which obviously only prints one equation number....

You could use empheq for that.

\documentclass{article}
\usepackage{empheq}
\begin{document}
\begin{subequations}
\begin{empheq}[left={\begin{aligned}
a &= b \\ c &=d