Answer:
a. The difference is '0'.
b. Approximately 120 beats/min
Explanation:
Looking at the graph, the woman's heart rate started at 60 beats/min before she began warming up for her workout. After she completed her cool-down, her heart rate was again at 60 beats/min. So, 60 - 60 = 0 difference.
The graph shows the woman's heart rate over time. Looking at the x-axis (time) at around 8 minutes and moving up the y-axis (heart rate), we can see that after 8 minutes her heart rate was approximately 120 beats/min.