Final answer:
To define the major and minor units on the vertical axis of a line chart, start the scale at 0 and continue up to a value that includes all the data points. For this particular example, a scale from 0 km to 160 km with a tick mark every 10 km should suffice.
Step-by-step explanation:
To define the major and minor units on the vertical axis of a line chart, you need to determine the best scale that shows all of your data and makes it easy to identify trends. In this case, the major unit is 20000 and the minor unit is 5000. You can start the scale at 0 and continue up to a value that includes all the data points. In this example, a scale from 0 km to 160 km with a tick mark every 10 km should suffice.