Answer:
.

Explanation:
Given that state sales tax y is directly proportional to retail price x.
This means that there is a constant k such that:

We are also given that an item that sells for 178 dollars has a sales tax of 10.22 dollars.
Let's plug these values into the equation y = kx.

Divide both sides by 178


Therefore, the mathematical model that gives the amount of sales tax y in terms of the retail price x is:
.
The sales tax on a 270 dollars purchase is:


So the answer is:
