Math

Can someone explain how to solve this system using substitution?

1.25x + 0.75y = 109.75
x + y = 105

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asked by Anonymous

  1. sure. the 2nd equation says that

    y = 105-x.

    Substitute that into the first equation to get

    1.25x + 0.75(105-x) = 109.75
    x = 62
    So, y = 105-62 = 43

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    posted by Steve

  2. 1.25x + 0.75y = 109.75
    x + y = 105 > x = 105 - y

    Put x value in the first equation;

    1.25(105 - y) + 0.75y = 109.75
    131.25 - 1.25y + 0.75y = 109.75
    131.25 - 0.5y = 109.75
    -131.25 -131.25
    ___________________________________

    -0.5y = -21.5
    ______ _______

    -0.5 -0.5

    y = 43

    Now solve for x. Use either equation.

    x = 105 - 43
    x = 62

    x = 62

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    posted by Chelle

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