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  1. #1
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    help

    in a chemistry class have a bottle of 5% boric acid solution and a bottle of 2% boric acid solution. It need 60 milliliters of a 3% boric acid solution for an experiment. how much of each solution is need to mix together? use linear equation systems of substitution and combination method.
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  2. #2
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    Hello, zasi!

    A chemistry class has a bottle of 5% boric acid solution and a bottle of 2% boric acid solution.
    It need 60 milliliters of a 3% boric acid solution for an experiment.
    How much of each solution is needed?
    We already know that the final mixure is 60 ml of 3% boric acid.
    . . That is, it contains: .0.03 60 .= .1.8 ml of boric acid. .[1]


    Let x = number of ml of the 5% solution.
    Let y = number of ml of the 2% solution.

    Then: .x + y .= .60 .[2]


    The x ml of 5% boric acid contains: 0.05x ml of boric acid.
    The y ml of 2% boric acid contains: 0.02y ml of boric acid.
    . . Hence, the mixture will contain: .0.05x + 0.02y ml of boric acid.

    But [1] says the mixture contains 1.8 ml of boric acid.

    There is our second equation! . 0.05x + 0.02y .= .1.8

    Multiply by 100: .5x + 2y .= .180 .[3]


    Solve the system formed by [2] and [3].

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