Here is the MWE:
\documentclass[preview, border&=5bp]{standalone}
\usepackage{tfrupee, amsmath, amssymb, mathtools}
\begin{document}
\begin{alignat*}{5}
\Aboxed{x + y &= 5 &&=15}\\
\Aboxed{p + q &= 27}\\
a + b &= 2 &&=11\\
a + b &= 2 &&=11
\end{alignat*}
\end{document}
The first equation with Abox is truncated, the second is not.
How do I get the box around the first equation also without truncation?
\Aboxedcan only have one & inside, because the macro is defined such that it reads all content up to the & and the content from the & to the end. Then the both parts are put into an\fboxand shifted right (by measuring the second half) such that they align with the rest. They have\fboxsolution there. Take a look at the link. – bp2017 Sep 10 '17 at 03:29