Resposta :
[tex]d=1\ km\\ t=20\ min=\frac{1}{3}\ h[/tex]
[tex]\boxed{v_m=\dfrac{d}{t}}\ \therefore\ v_m=\dfrac{1}{\frac{1}{3}}\ \therefore\ \boxed{v_m=3\ km/h}[/tex]
[tex]d=1\ km\\ t=20\ min=\frac{1}{3}\ h[/tex]
[tex]\boxed{v_m=\dfrac{d}{t}}\ \therefore\ v_m=\dfrac{1}{\frac{1}{3}}\ \therefore\ \boxed{v_m=3\ km/h}[/tex]