[tex]R_{1}=8 \ \Omega+4 \ \Omega=12 \ \Omega \\ R_2=\frac{12 \ \Omega+12 \ \Omega}{(12 \ \Omega)^2}=\frac{24 \ \Omega}{144}=\frac{1}{6} \ \Omega; \\ R_3=4 \ \Omega+\frac{1}{6} \ \Omega=\frac{25 \ \Omega}{6}; \\ R_4=\frac{\frac{25}{6} \ \Omega+10 \ \Omega}{\frac{25}{6} \ \Omega \cdot 10 \ \Omega}=\frac{15}{50} \ \Omega; \\ R_{T}=\frac{15}{50} \ \Omega+3 \ \Omega=\frac{15}{50} \ \Omega+\frac{150}{50} \ \Omega=\frac{165}{50} \ \Omega=\frac{33}{10} \ \Omega=\boxed{\bold{3,3 \ \Omega}}[/tex]
