Question

 

mn giúp em bài này vs ạ

Answer 1

\(\left\{{}\begin{matrix}v_1=\dfrac{s_1}{t_1}=\dfrac{120}{20}=6\left(\dfrac{m}{s}\right)\\v_2=\dfrac{s_2}{t_2}=\dfrac{60}{30}=2\left(\dfrac{m}{s}\right)\\v_{tb}=\dfrac{s_1+s_2}{t_1+t_2}=\dfrac{120+60}{20+30}=3,6\left(\dfrac{m}{s}\right)\end{matrix}\right.\)