如何在数学模式中使用抽认卡进行 & 对齐？

Question

所以我的概念是：

\documentclass[avery5388,grid,frame]{flashcards}

\usepackage{amsmath}
\usepackage{graphicx}

\cardfrontstyle[\large\slshape]{headings}
\cardbackstyle{empty}
\begin{document}

\cardfrontfoot{Calculus}

\begin{flashcard}[\raisebox{\depth}{\scalebox{-1}[-1]{Calculus}}]{Derivation}

\medskip

\textbf{Formula:} 
\begin{align*}
P(x) &= x^2+p\,x+q \\ %this & is causing the problem I assume. 
     &= ...
\end{align*}
\end{flashcard}

\end{document}