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