Question

The sales tax on a digital camera is $7.15. What is the sales tax rate?

Answer 1

You just have to find out the percent 7.15 is of 105.  To do that, you set up a proportion with x as the percentage:

$\frac{7.15}{105}=\frac{x}{100}$

Then, cross multiply to get:

$\frac{7.15}{105}=\frac{x}{100}\\715=105x\\105x/105=715/105\\x=6.810$

So, the sales tax rate was 6.8%.