Answer:
<em>a) She started walking back</em>
<em>b) 0.13 km/min</em>
Step-by-step explanation:
The graph shows the distance traveled by Jo. She starts her journey (t=0) at a distance of 0 Km since the graph passes through the origin (0,0).
a) Ten minutes later she is at a distance of 1 km from the starting point and then the distance starts to drop. This means that at t=10 minutes, she started walking back.
b) To calculate the speed for the last 30 minutes of journey, we find the slope of the line. Select the points (30,0) and (60,4).
If a given line passes through points A(x1,y1) and B(x2,y2). The slope can be calculated with the equation:

Substituting:

v=0.13 km/min