\\
R_r = \frac{R_1 R_2}{R_1 + R_2} = \frac{199,1 * 161,1}{199,1 + 161,6} = \frac{32174,56}{360,7} = 89,20033\Omega \\
\Delta R_r = \frac{R_2^2 \Delta R_1}{(R_1 + R_2)^2} + \frac{R_1^2 \Delta R_2}{(R_1 + R_2)^2} = \frac{161,6^2 * 2}{(199,1 + 161,6)^2} + \frac{199,1^2 * 1,6}{(199,1 + 161,6)^2} = \frac{52229,12}{130104,49} + \frac{63425,296}{130104,49} = 0,8889348 \approx 0,9\Omega \\\\
R_r = 89,2 \pm 0,9\Omega