\begin{frame}
\begin{itemize}
\item To reduce a fraction, we use the rule:
\[
\uncover<2->{ \frac{x \cdot a}{x\cdot  b} =}\frac{\fcCancel{2}{x}\cdot a}{\fcCancel{2}{x}\cdot b}= \frac{a}{b}.
\]
\item<2-> To reduce excessive copying: use cancel notation.
\item<3-> The uses of the cancel notation will become apparent in examples.
\item<4-> Rules. 
\begin{itemize}
\item Use a single slanted line. 
\item Unless circumstances dictate otherwise, slant your line from lower left corner to top right corner. 
\item Do not use crosses, smudges, or any other notation that obscures the expression below the cancel line.
\end{itemize}

\end{itemize}


\end{frame}