To find slope, you can use your two points in ysub1-ysub2/xsub1-xsub2
(2,60) and (6,120) are your points
120-60 60
———— = ——— = 15
6-2 4
Therefore, your slope is 15 or 15/1
This means the money earned increases by $15 for each hour worked
Hope this helps! :)