An item that sells for $145.99 has a sales tax of 10.22

Find a mathematical model that gives the amount of sales tax y in terms of the retail price x

Use the model to find the sales tax on a purchase that has a retail price x

I assume you mean $10.22

So the rate is 10.22/145.99 = .07 or 7%

y = .07x

To find a mathematical model that gives the amount of sales tax y in terms of the retail price x, we can use the formula:

y = x * r

where:
y represents the amount of sales tax
x represents the retail price of the item
r represents the sales tax rate (in decimal form)

In this case, the sales tax rate is 10.22%, which needs to be converted to a decimal by dividing it by 100:

r = 10.22% / 100 = 0.1022

Now, we can substitute the values into the formula to find the mathematical model:

y = x * 0.1022

To find the sales tax on a purchase that has a retail price x, you can simply substitute the given retail price into the model. For example, if the retail price is $200, the sales tax would be:

y = 200 * 0.1022 = $20.44

Therefore, the sales tax on a purchase with a retail price of $200 would be $20.44.