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Math Help - Word problem involving currency...

  1. #1
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    Word problem involving currency...

    I've tried several equations to no avail. Please help

    "A person changed $200 into five- and ten- dollar bills. The person then had 28 bills in all. How many ten-dollar bills were there? What was the value of the five-dollar bills?"
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    Re: Word problem involving currency...

    Quote Originally Posted by Builderjay2011 View Post
    I've tried several equations to no avail. Please help

    "A person changed $200 into five- and ten- dollar bills. The person then had 28 bills in all. How many ten-dollar bills were there? What was the value of the five-dollar bills?"
    f = number of $5 bills

    t = number of $10 bills

    solve the system of equations ...

    f + t = 28

    5f + 10t = 200
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    Re: Word problem involving currency...

    Sorry I do not understand.
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    Re: Word problem involving currency...

    Quote Originally Posted by Builderjay2011 View Post
    Sorry I do not understand.
    what do you not understand? the meaning of each the equation and how they came about, or how to solve them?

    what methods for solving systems of equations have you already learned?

    you have to help out here, jay ... hard to read minds over cyberspace.
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    Re: Word problem involving currency...

    Does this make any sense? My teacher showed me this set-up which was totally different from yours.

    Let 5f = number of five dollar bills
    Let 10(28-f) = number of ten-dollar bills

    200 = 5f + 10(28-f)
    200 = 5f + 280-10f
    200 - 280 = 5f - 10f
    -80 = -5f

    f = 16 number of five-dollar bills
    28 - 16 = 12 number of ten-dollar bills
    $120.00 value of ten-dollar bills
    $80.00 value of five-dollar bills
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    Re: Word problem involving currency...

    Quote Originally Posted by Builderjay2011 View Post
    Does this make any sense? My teacher showed me this set-up which was totally different from yours.

    Let 5f = number of five dollar bills
    Let 10(28-f) = number of ten-dollar bills

    200 = 5f + 10(28-f)
    200 = 5f + 280-10f
    200 - 280 = 5f - 10f
    -80 = -5f

    f = 16 number of five-dollar bills
    28 - 16 = 12 number of ten-dollar bills
    $120.00 value of ten-dollar bills
    $80.00 value of five-dollar bills
    5f is the amount of money the number of 5 dollar bills are worth

    if f + t = 28

    then t = 28-f = the number of $10 bills

    the amount of money in $5 bills + the amount of money in $10 bills = total money

    5t + 10(28-f) = 200
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    Re: Word problem involving currency...

    Quote Originally Posted by Builderjay2011 View Post
    Does this make any sense? My teacher showed me this set-up which was totally different from yours.

    Let 5f = number of five dollar bills
    Let 10(28-f) = number of ten-dollar bills

    200 = 5f + 10(28-f)
    200 = 5f + 280-10f
    200 - 280 = 5f - 10f
    -80 = -5f

    f = 16 number of five-dollar bills
    28 - 16 = 12 number of ten-dollar bills
    $120.00 value of ten-dollar bills
    $80.00 value of five-dollar bills
    If that's EXACTLY what your teacher showed, then your teacher needs further training!

    "Let 5f = number of five dollar bills": that' s not the number of $5 bills, it's the VALUE of the $5 bills.

    Did your teacher not show this way:
    Let f = number of $5 bills; then 28-f = number of $10 bills?
    Then proceeded to:
    5f + 10(28 - f) = 200
    ?????
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  8. #8
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    Re: Word problem involving currency...

    In problems like this one it is usually easier to write an equation in one unknown
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    Re: Word problem involving currency...

    Quote Originally Posted by bjhopper View Post
    In problems like this one it is usually easier to write an equation in one unknown
    I'd say "always easier" BJ !
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