Results 1 to 2 of 2

Thread: Finding Original Amount

  1. #1
    Mar 2008

    Finding Original Amount

    If I have $20 at 7% tax, I get a total of $21.40. If I use this equation:

    $21.40/1.07 = $20, it will give me by base amount before the tax was added on.

    What I need to know is if I have ($10 + ($10 + (10 * 7%))), I get a total of $20.70. How do I find out what the base amount of this is? I cant use $20.70/1.07 to get my base amount of $20 because only $10 of it is figured at the 7% rate. I need to know if there is a way to get the base amount om this scenario? Any help would be greatly appreciated.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member topher0805's Avatar
    Jan 2008
    You have $10 that is not taxed. You are adding to that another $10 plus tax.

    So, minus $10 from your end amount of $20.70 to get $10.70.

    Then use your formula:

    $\displaystyle \frac {10.70}{1.07} = 10$

    So, your original amount was $20.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Finding amount of numbers.
    Posted in the Discrete Math Forum
    Replies: 2
    Last Post: Mar 10th 2010, 12:28 AM
  2. Replies: 5
    Last Post: Feb 3rd 2010, 05:08 PM
  3. Finding amount before taxes..
    Posted in the Business Math Forum
    Replies: 2
    Last Post: Oct 23rd 2009, 03:51 AM
  4. Exponential radioactive decay while original amount increases.
    Posted in the Differential Equations Forum
    Replies: 5
    Last Post: Jun 27th 2008, 08:01 PM
  5. Replies: 1
    Last Post: Dec 3rd 2007, 11:58 PM

Search Tags

/mathhelpforum @mathhelpforum