An item costs $420 before tax, and the sales tax is$ 16.80 whats the sale tax rate

We need to set up an equation to solve this problem.  The sales tax is a percentage of the total, so that's what we are looking for.

Let's call S our sales tax

So, that's what we are looking for, and we are given the actual sales tax

So now we have a decimal.  In order to convert a decimal into a percentage, we must multiply by 100 (since percentages are out of 100)

The sales tax rate is 3.8%

she played for 18.75 hours.

step-by-step explanation:

if she played 2/4 of a hour on tuesday. and there is 60 minutes in an hour and 60 divided by 4 is 7.5. and she played 2/4 of an hour on thursday then again 60 divided by 4 is 7.5, you add 7.5+7.5=56.25. now you have to do 1/4 of an hour, it equals 3.75. now you have to add them all up. 3.75+7.5+7.5=18.75

i hope this and i hope you get it right. it took me a while to get this done for you. : )

in mathematics, a constraint is a condition of an optimization problem that the solution must satisfy. there are several types of constraints—primarily equality constraints, inequality constraints, and integer constraints. the set of candidate solutions that satisfy all constraints is called the feasible set.

hoped i'm right lol