Draw a graph of Barbaras distance from home (in blocks) as a function of time.

Draw a coordinate plane.

Barbara leaves home(plot the point ).

Walks 2 blocks in 5 minutes at a constant speed(plot the point ).

And realizes that she forgot to lock the door. So Barbara runs home in 1 minute(plot the point ).

While at her doorstep, it takes her 1 minute to find her keys and lock the door(plot the point (7, 0)).

Barbara walks 5 blocks in 15 minutes(plot the point ).

And then decides to jog home. It takes her 7 minutes to get home(plot the point ).

Connect all those points.

The graph is :

.

The graph is:

.