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bill k
Lv 6
bill k asked in Science & MathematicsMathematics · 1 year ago

Find value?

Please explain step by step how to mathematically prove the following:

x + y = 100

Find the value of x and y when x = y.

Obviously the answer is 50 but how do I get that answer mathematically?

4 Answers

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  • ?
    Lv 7
    1 year ago

    x + y = 100   

    When x = y

    2y = 100

    y = 50 and x = 50 

  • Lisa A
    Lv 7
    1 year ago

    YOu have two simultaneous equations in two variables/

    x=y

    x+y=100

    So you can take the first equation, and substitute x for y into the second equation.

    x + x = 100

    2x = 100

    x = 100/2

    x = 50

  • iansand
    Lv 7
    1 year ago

    Substitute x for y

    x+x=100

    2x=100

    Halve both sides

    x=50

  • ?
    Lv 7
    1 year ago

    x + y = 100

    x + x = 100 as x = y

    2x + 100

    x = 100/2 = 50

    and y = x = 50

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