Question

the sales tax for an item was $7.80 and it cost $390 before tax. find the sales tax rate. write your answer as a percentage.

Answer 1

$390 represent 100%. To find what percentage $7.80 represent, we can use the next proportion:

`\frac{390\text{ \$}}{7\text{.8 \$}}=\frac{100\text{ \%}}{x\text{ \%}}`

Solving for x,

`\begin{gathered} 390\cdot x=100\cdot7.8 \\ x=(780)/(390) \\ x=2\text{ \%} \end{gathered}`

The sales tax rate is 2%