PLEASE HELP A local boutique sells water bottles for a set price, plus an additional fee for each letter that customers would like engraved on their water bottle. The pricing for up to 4 engraved letters is shown in the table below. Write an equation in slope-intercept form to represent the relationship between the number of letters and the total cost.
#of letters = 0, 1, 2, 3, 4
Total cost= 18.99,1 9.34, 19.69, 20.04, 20.39