To find an equation to describe the relationship between t and c you:
1. Find what is the dependent variable and the independent variable
In this case the total cost of the tickets depend of the number of tickets. Then:
Dependent variable is C
Independent variable is T
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You can see in the table that the difference between the cost of the tickects is 165 for every 3 tickets. you find this by substracting the data in every column, as follow:
Then, the equation will be a lineal equation with a slope of:
You use a point of the lineal relationship to find the equation:
(2,110) t1=2 c1= 110
You use the next formula:
You replace the coordinates of the point and find the value of b:
The equation is: