The second question, let the vehicle speed x, the human speed y, 2(x+y)=6(x-y), and get x=2y, then the time is 2 (meeting time) *(x+y)/x=3 minutes.
Use equations
Set the vehicle speed v and the human speed v 1, and send a car in t minutes.
Then:
2(v+v 1)=vt
6(v-v 1)=vt
v=2v 1
2(2v 1+v 1)= 2v 1t
6v 1=2v 1t
t=3
A tram leaves the station every three minutes.