From: Gail (for Teacher2Teacher Service)
Date: May 07, 2008 at 23:19:13
Subject: Re: Sales Tax Computation (Backwards)

Hi Barry,

How do we find the amount of sales tax on a certain amount? We multiply the
amount by the tax rate, and add that product to the original amount, right?
So, we really have 100% of the amount, plus however much, percent-wise, the
tax is.  In this case, the tax is 7%, so we would have 107% times whatever
the amount was.

So, if you wanted to know how much you needed to spend, you could just set
it up as an equation.  You know you are going to spend a certain amount x,
and that, together with the tax you will spend 107% of x to make $500.

107% x = 500
1.07x = 500
1.07x/1.07 = 500/1.07  Divide both sides by 1.07 to isolate x.

So, x = 500 divided by 1.07...   I will let you figure out the rest of it.

 -Gail, for the T2T service

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