Total cost = 1.50 per bottle y = 1.50x If x = 1, y = $ 1.50 (1,1.5) If x = 2, y = $ 3.00 (2,3) If x = 3, y = $ 4.50 (3, 4.5) If x = 4, y = $ 6.00 (4, 6) There are your 4 sets of ordered pairs to graph. You could continue with more x-values to get more ordered pairs.
(Sample answer) Make a table with inputs showing the number of bottles of water and outputs showing the total cost of the water. Use 1, 2, 3, and 4 bottles for the inputs. Find the corresponding outputs. Plot the ordered pairs in the table of the form (input,output).