A pack of cinnamon-scented pencils sells for $6.00. What is the sales tax rate if the total cost of the pencils is $6.42?

7%

Step-by-step explanation:

The additional tax is $0.42, we just have to find how much percent the tax ($0.42) is of the original cost ($6.00).

To do this, we can use the following formula:

Where x is the part (in this case, the tax ($0.42)), y is the whole (in this case, the original cost ($6.00)), and p being the percent (the tax rate in this case). We can replace the values in:

We can cross multiply and simplify to find the tax rate:

We're not done yet! We still need to turn it to percent. But we can do this by just multiplying our result by 100:

Place the percent sign and we are done.

Hope this helps.