# Problems With Sales Tax

by Deja
(Cleavland,Ohio,USA)

The Sheng family had dinner at their favorite restaurant. A 10% sales tax was added to their bill. Amy paid the bill with a \$20 gift certificate plus \$23.5. How much did the family's dinner cost before tax? Round your answer to the nearest penny.

### Comments for Problems With Sales Tax

Average Rating     Sep 24, 2010 Rating     Problems With Sales Tax by: Karin Let's first talk about the things that we know in this problem. 1. We know that the total bill was \$43.50. Amy paid with a \$20 gift certificate, plus 23.50. (20+23.50 = 43.50) 2. We know that 10% sales tax was added to the bill. We know that we must convert the % to a decimal and round it to the pre-tax total. The question is, "What is the pre-tax total? Or How much was the original bill?" We will need to write an equation and solve. Let's first write the equation in words: Original bill + 10% tax = Total We'll let the original bill = x since we don't know that total. Original bill + 10% tax = Total x + .1x = 43.50 (Remember that for tax you multiply the decimal times the original amount) Now we need to combine like terms. (1x + .1x = 1.1x) 1.1x = 43.50 Now we will divide both sides by 1.1 1.1x/1.1 = 43.5/1.1 x = 39.55 The original bill was \$39.55 Now let's check to see if this is correct. 39.55 + 39.55(.10) = 39.55 + 3.96 = 43.51 Due to rounding issues, we are 1 penny off, but this is the correct answer. I hope this helps, Karin