E) Evelyn bought a new smartphone for $499 plus tax. She was surprised when she got
the receipt and saw that the tax was $42.42. What was the sales tax rate for this
purchase?

Respuesta :

Translating "The tax is some percent of the phone's price" into an equation, we get:

   42.42 = p · 499

If we divide both sides by 499, we get

   0.085 ≈ p

We can check by finding 8.5% of 499:

   0.085 · 499 = 42.415, which rounds to 42.42

So the tax rate was 8.5%.