An independent variable is a variable that does not dependent on other variables. It is the input variable.
A dependent variable is a variable that is dependent on other variables. The dependent variable depends on the independent variable. It is the output variable.
Since porter receives 3 tickets for every dollar, this means the number of ticket is dependent on the money he spend. Therefore the money he spends (d) is the independent variable and the tickets (t) is the dependent variable.
99(15) = 1.35x14.85 = 1.35x14.85/1.35 = 11 I think it is 15. I am not sure about the proper way to solve this....I just know that if he sold 15 brownies, he could buy 11 packs with exactly no change left over.