[tex]\bf \begin{cases}
u=13j\implies 0i+13j\implies \ \textless \ 0,13\ \textgreater \ \\
v=i+3j\implies 1i+3j\implies \ \textless \ 1,3\ \textgreater \
\end{cases}
\\\\\\
\ \textless \ 0,13\ \textgreater \ \cdot \ \textless \ 1,3\ \textgreater \ \implies (0\cdot 1)+(13\cdot 3)\implies 39[/tex]
