Finance calculator question. How do I get the original price of something if I know the tax and whole dollar?

Question

For my homework we are supposed to sell lemonade for $1, Pizza and fries for $5 and Pizza, Fries, lemonade, and dessert for $10. How do I find the original selling price if the above prices already include the tax of .975???? How do I do it by hand or by business finance calculator.

So the answer to the first amount of $1 would be like .92 cents or something plus the .975 tax to = $1. I don't think it's 92 cents but that's close.

okay thanks!!!!!

Answer 1

Sale amount = Price + Tax

Sale amount = Price + (Price * 0.0975)

Sale amount = Price * 1.0975

Now solve for Price:

Price = Sale amount / 1.0975

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Sale amount $1 => Price = $0.91

Sale amount $5 => Price = $4.56

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In general, for any tax rate x

Price = Sale amount / (1 + x )