Answer
The table and the graph for the relationship is attached below.
The equation for the relationship is C=3x, where C represents the cost and x represents the number of cartons of egg.
Work Step by Step
The equation for the relationship was C=3x because each carton costs $3 which is the slope of the graph and so m=3 and x is the independent variable as the total cost depends on the number of cartons of egg bought. C is the dependent variable (i.e. y) as it depends on the number of cartons bought.
The equation of a line is y=mx+b and in this question the slope is 3 so it becomes C=3x
