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Math Help - solving basic equations

  1. #1
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    solving basic equations

    The cost of a meal, including a 20% tip, is $21.60. How much was the meal without the tip?
    The tip is 20% of x or 0.2x
    Together, x + 0.2x =$21.60
    1.2x =21.6
    x = 18
    what does x = in 0.2x and how would you find it
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  2. #2
    Member TheMasterMind's Avatar
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    Quote Originally Posted by Leona_Marie View Post
    The cost of a meal, including a 20% tip, is $21.60. How much was the meal without the tip?
    The tip is 20% of x or 0.2x
    Together, x + 0.2x =$21.60
    1.2x =21.6
    x = 18
    what does x = in 0.2x and how would you find it
    0.2 x is the percentage (20%) as a decimal
    Last edited by TheMasterMind; January 23rd 2009 at 12:57 PM.
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  3. #3
    Senior Member mollymcf2009's Avatar
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    Originally Posted by Leona_Marie
    The cost of a meal, including a 20% tip, is $21.60. How much was the meal without the tip?
    The tip is 20% of x or 0.2x
    Together, x + 0.2x =$21.60
    1.2x =21.6
    x = 18
    what does x = in 0.2x and how would you find it


    When you want to find out what the percentage of something is, you multiply it by that percentage. If you have 20% of $1 you have 20 cents.

    Think about it this way: If you have $1.00, you have 100% of it. If you give me 20 cents you will have $0.80 cents left over. Look at what 80 cents look like --> 0.80 which is the same as 80%
    So you gave me 20% of your dollar and you have 80% left.

    x is your unknown value. What is the unknown value that the question asks for or what are you trying to find by solving this equation? The original cost of the meal, right? So that is what x would be!
    x + .2x = 21.6 --> x = original cost of meal, .2x = cost of meal x 20% of that cost
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  4. #4
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    Quote Originally Posted by mollymcf2009 View Post
    Originally Posted by Leona_Marie
    The cost of a meal, including a 20% tip, is $21.60. How much was the meal without the tip?
    The tip is 20% of x or 0.2x
    Together, x + 0.2x =$21.60
    1.2x =21.6
    x = 18
    what does x = in 0.2x and how would you find it


    When you want to find out what the percentage of something is, you multiply it by that percentage. If you have 20% of $1 you have 20 cents.

    Think about it this way: If you have $1.00, you have 100% of it. If you give me 20 cents you will have $0.80 cents left over. Look at what 80 cents look like --> 0.80 which is the same as 80%
    So you gave me 20% of your dollar and you have 80% left.

    x is your unknown value. What is the unknown value that the question asks for or what are you trying to find by solving this equation? The original cost of the meal, right? So that is what x would be!
    x + .2x = 21.6 --> x = original cost of meal, .2x = cost of meal x 20% of that cost
    molly, thank you that was the answer I was looking for
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