State sales tax is based on retail price. An item that sells for $115.99 has a sales tax of $8.12. Find a mathematical model that gives the amount of sales tax y in terms of the retail price x. (Round the coefficient to two decimal places.)

y =

Use the model to find the sales tax on a $530.50 purchase. (Round your answer to the nearest cent.)
$

2 answers

rate = 8.12/115.99 = .070006035
but since the $8.12 was most likely rounded off to the nearest cent, I would say it was .07 or 7%

so y = .07x

so when x = 530.50
y = .07(530.50) = $37.14
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