The total cost of an item including sales tax is directly proportional to its price. if the total cost of a $32 item is $33.60 , what is the total cost on a $55 item

Let the total cost of the item be represented by C and the price be represented by P, then given that the total cost of an item including sales tax is directly proportional to its price, thus



where k is a constant.

Given that the total cost of a $32 item is $33.60, thus



Therefore, the total cost on a $55 item is given by