$${\frac{{log}_{10}\left({\mathtt{0.5}}\right)}{{log}_{10}\left({\mathtt{a}}\right)}} = {\mathtt{3}}$$ => $${\mathtt{3}}{\mathtt{\,\times\,}}{log}_{10}\left({\mathtt{a}}\right) = {log}_{10}\left({\mathtt{0.5}}\right)$$
$${\mathtt{3}}{\mathtt{\,\times\,}}{log}_{10}\left({\mathtt{a}}\right) = {log}_{10}\left({\mathtt{0.5}}\right) \Rightarrow {\mathtt{a}} = {{\mathtt{e}}}^{{\mathtt{\,-\,}}\left({\frac{{\mathtt{13\,614\,799}}}{{\mathtt{58\,926\,009}}}}\right)} \Rightarrow {\mathtt{a}} = {\mathtt{0.793\: \!700\: \!525\: \!984\: \!099\: \!6}}$$
$${\frac{{log}_{10}\left({\mathtt{0.5}}\right)}{{log}_{10}\left({\mathtt{a}}\right)}} = {\mathtt{3}}$$ => $${\mathtt{3}}{\mathtt{\,\times\,}}{log}_{10}\left({\mathtt{a}}\right) = {log}_{10}\left({\mathtt{0.5}}\right)$$
$${\mathtt{3}}{\mathtt{\,\times\,}}{log}_{10}\left({\mathtt{a}}\right) = {log}_{10}\left({\mathtt{0.5}}\right) \Rightarrow {\mathtt{a}} = {{\mathtt{e}}}^{{\mathtt{\,-\,}}\left({\frac{{\mathtt{13\,614\,799}}}{{\mathtt{58\,926\,009}}}}\right)} \Rightarrow {\mathtt{a}} = {\mathtt{0.793\: \!700\: \!525\: \!984\: \!099\: \!6}}$$