The domain is anything x is and the range is anything y is. Therefore, to find the domain and ranges in #16 and #18, just copy down the numbers from the charts.
#16
Domain (x): 100, 120, 150, 170
Range (y): 5.4, 3.5, 2.7, 0.2
#18
Domain (x): 20, 25, 35, 40
Range (y): 12, 15, 21, 24