A person goes from his home to his office taking one hour. There he works for 2 hours and then in half hour reaches home back. A representative displacement-time graph is
Take the reference point home as the origin.
1 hour: With respect to home the person moves to office: Motion is along +x axis.
2 hours: He stays at rest there
1/2 an hour: He moves back towards home: his x-coordinate with respect to the origin decreases.