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Math Help - Easy word problem has me stumped

  1. #1
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    Easy word problem has me stumped

    For the person responding, can you please explain the logic of how you set up the equation.

    Thank anyone who responds in advance

    Q) The sum of two numbers is 15. Three times one of the numbers is 11 less than five times the other. Find the numbers.

    *from the back of the book, I already know that the answer is 6, 7,

    What I put together was
    3x=5x-11 but considering that there are two number to answer for, I realize I am wrong.
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  2. #2
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    so sorry I posted in the wrong forum
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  3. #3
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    Let the 2 numbers be x and y. Then on the first sentence you have,

    x + y = 15

    in the second sentence you have 3x = 5y - 11

    Solve the first equation for x or you could use y if you like and substitute it into the second equation.

    So x = 15 - y. Then you have

    3(15 - y) = 5y - 11
    45 - 3y = 5y - 11

    Solve for y

    56 = 8y
    7 = y

    substitute the 7 for y into one of the original equations

    x + 7 = 15
    x = 8

    not sure where they got the 6 from in the back of book
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