sales tax formula

[chocolatelover]

Hi everyone,

1. The problem statement, all variables and given/known data
A child is surprised that she must pay $1.40 for a toy marked $1.25 because of sales tax. What is the effective tax rate on this purchase?

2. Relevant equations



3. The attempt at a solution

I know that the difference between the two is .15. I could just guess and check, but is there a formula?

Thank you very much

[awvvu]

Try thinking about how tax is computed.

1.25 * r = 0.15

[chocolatelover]

Thank you very much

Regards