You can put the dollars on the y axis and the hours on the x axis. Whenever the hours increase by 1, move over 1 on the x axis and 7.50 up on the y axis.
The first point should be (1, $7.50). ↑ ↑ hours, money earned
The second point then will be (2, $15.00), the third will be (3, $22.50), and so on.
