A catering company uses different functions to estimate the itemized costs for a party. The table below represents the included tip for wait staff as a function of the number of guests served. A table showing Catering Cost for Wait Staff Gratuity with two columns and 6 rows. The first column has, Number of Guests, and has the entries, 10, 20, 30, 40, 50. The second column, Wait Staff Tip, has the entries, $18, $36, $54, $72, $90. If the tip varies directly with the number of guests, which equation represents the relationship between the tip, t, and the number of guests, g?