The graph below shows the numbers of cups of orange juice that are mixed with different numbers of cups of lemon-lime soda to make servings of orange soda:

A graph is shown. The values on the x-axis are 0, 1, 2, 3, 4, 5. The values on the y-axis are 0, 3, 6, 9, 12, 15. Points are shown on ordered pairs 0, 0 and 1, 3 and 2, 6 and 3, 9 and 4, 12. These points are connected by a line. The label on the x-axis is Lemon lime Soda in cups. The title on the y-axis is Orange Juice in cups.

What is the ratio of the number of cups of orange juice to the number of cups of lemon-lime soda?