From (0~0.8)h, after 0.8h, it traveled 1.6km, that is, AD= 1.6km.

So the speed is1.6/0.8 = 2 km/h.

CD= 1km, driving time:1/2 = 0.5h.

Then use 1.8h-0.5h= 1.3h (that is, the number corresponding to the dotted line between 0.8 and 1.8 on the image! )

1.3-0.8=0.5h is the residence time!

1.8h+0.5h=2.3h is the departure time from point C!

3h to point A, 3 h later-2.3 h = 0.7 h.

CA = CE+AE = 2km/h x 0.7h = 1.4km

Ce = ca-AE =1.4km-0.8km = 0.6km.