[tex]N(t)=N_{\circ}(\frac{1}{2})^{\frac{t}{t_{\circ}}}[/tex][tex]\begin{gathered} \text{where} \\ N(t)=quantity\text{ remaining} \\ N_{\circ}=Initial\text{ substance} \\ t=time\text{ elapsed} \\ t_{\circ}=half\text{ life} \end{gathered}[/tex][tex]\begin{gathered} N(t)=12.5g \\ N_{\circ}=100g \\ t=25.3\text{ days} \\ t_{\circ}=? \end{gathered}[/tex][tex]undefined[/tex]
