50=131,4 log 3/d

$${\mathtt{50}} = {\frac{{\mathtt{131.4}}{\mathtt{\,\times\,}}{log}_{10}\left({\mathtt{3}}\right)}{{\mathtt{d}}}}$$

$${\mathtt{50}}{\mathtt{\,\times\,}}{\mathtt{d}} = {\mathtt{131.4}}{\mathtt{\,\times\,}}{\mathtt{log3}}$$          =>        $${\mathtt{d}} = {\frac{{\mathtt{131.4}}{\mathtt{\,\times\,}}{log}_{10}\left({\mathtt{3}}\right)}{{\mathtt{50}}}}$$

  d =   $${\frac{{\mathtt{131.4}}{\mathtt{\,\times\,}}{log}_{10}\left({\mathtt{3}}\right)}{{\mathtt{50}}}} = {\mathtt{1.253\: \!874\: \!657\: \!403\: \!272\: \!9}}$$