The graph shows the amount of money paid when purchasing bags of candy at the zoo:

a graph is shown. the x-axis is labeled from 0 to 9. the y-axis is labeled from 0 to 10. the four points shown on the graph are ordered pairs 0, 0 and 1, 2 and 2, 4 and 3, 6. these points are joined by a line. the label on the x-axis is bags of candy. the title on the y-axis is total cost in dollars.

write an equation to represent the relationship between the total cost (y) and the number of bags of candy (x).

y = one-half x
y = 2x
y = 3x
y = one-third x