Know :$\displaystyle \left\{ \begin{array}{l}
\log _a \left( b \right) = \frac{2}{3} \\
lug_c \left( d \right) = \frac{4}{5} \\
a - c = 9 \\
\end{array} \right.
$
calculate :$\displaystyle b - d$
a,b,c,d naturels numbers.