41. For a real number $x$, the symbol $[\mathrm{x}]$ represents the greatest integer not greater than $x$, for example $[0.3]=0,[\pi]=3,[-2.5]=-3$. If $\left[\frac{x+4}{10}\right]=5$, then the maximum value of $\left[\frac{6 x}{5}\right]$ is . $\qquad$