Consider the context free grammar:$\qquad \begin{align}    \mathrm{bill} &\to \mathrm{items}\ \mathrm{total}\ \mathrm{vat} \\    \mathrm{items} &\to \mathrm{item} \mid \mathrm{item}\ \mathrm{items} \\    \mathrm{item} &\to name\ \mathrm{price} \mid name\ \mathrm{quantity}\ \mathrm{price} \\    \mathrm{quantity} &\to integer \\    \mathrm{price} &\to integer \\    \mathrm{total} &\to integer \mid TOTAL\ \mathrm{price}  \\    \mathrm{vat} &\to VAT\ \mathrm{price}  \end{align}$How do I factor the grammar?This was asked in a past exam, and I don't know how to get started.Also, if you have any links that could help me understand this more it would be much appreciated!
Factor a grammar
formal languages;formal grammars;context free