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Thread: Ratio/Proportion: Given: A/B=7/9 and C/D=5/3; If B=4D, compute A+B/C+D

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    Ratio/Proportion: Given: A/B=7/9 and C/D=5/3; If B=4D, compute A+B/C+D

    The problem is "Given: A/B=7/9 and C/D=5/3; If B=4D, compute A+B/C+D". It's not homework, just a practice problem, so no rush (not that there would be anyway, but you know). I don't really understand how to start. I've tried a lot of things, basically just creating equations and substituted, but nothing has worked. I'd appreciate if someone could show me how to begin finding the variables. Thanks!

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    Quote Originally Posted by lei View Post
    Given: A/B=7/9 and C/D=5/3; If B=4D, compute (A+B)/(C+D)

    I've tried a lot of things, basically just creating equations and substituted, but nothing has worked.
    Those grouping symbols are very important; please ask, if you don't understand why.

    You were probably on the right track, with some of your starts; maybe you didn't go far enough, before starting over. You didn't show any work, so I'm not sure what you tried.

    Setting the cross-products equal to one another might be a good start.

    9A = 7B

    3C = 5D

    Replace that B with 4D, and simplify: 9A = ?D

    Expressions 9A and ?D represent the same number. We can divide each side of the equation 3C=5D by that number.

    There are other ways to begin; I showed one example.

    Next time you post, please show us your steps. Thank you.
    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

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    Thanks!

    Quote Originally Posted by mmm4444bot View Post
    Those grouping symbols are very important; please ask, if you don't understand why.

    You were probably on the right track, with some of your starts; maybe you didn't go far enough, before starting over. You didn't show any work, so I'm not sure what you tried.

    Setting the cross-products equal to one another might be a good start.

    9A = 7B

    3C = 5D

    Replace that B with 4D, and simplify: 9A = ?D

    Expressions 9A and ?D represent the same number. We can divide each side of the equation 3C=5D by that number.

    There are other ways to begin; I showed one example.

    Next time you post, please show us your steps. Thank you.
    Thank you so much, I got the answer, I just hadn't gone far enough like you said

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