Resposta :
* 240/x=t > tx=240 (-1)
*400/x=t+2> tx+2x= 400
-tx=-240
+tx+2x= 400
2x= 160
x=80 km/h
t= 240/80 = 3 horas
*400/x=t+2> tx+2x= 400
-tx=-240
+tx+2x= 400
2x= 160
x=80 km/h
t= 240/80 = 3 horas