Let b,n,p be the price of a book,a notebook and a pen in VND respectively.We have :

\(\left\{{}\begin{matrix}b+6n+3p=7700\\8b+6n+6p=16000\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}b=7700-6n-3p\\6n=7700-b-3p\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}8\left(7700-6n-3p\right)+6n+6p=16000\\8b+\left(7700-b-3p\right)+6p=16000\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}61600-42n-18p=16000\\7b+3p=8300\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}42n+18p=45600\\7b+3p=8300\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}7n+3p=7600\left(1\right)\\7b+3p=8300\left(2\right)\end{matrix}\right.\)

\(\left(2\right)-\left(1\right)=7\left(b-n\right)=700\Rightarrow b-n=100\)

So,the price of a book is more than the price of a notebook by 100 VND.