Math

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1.Sally age is 12 years plus half her age. How old is she?


2.Given that: 4x-y+9=0 and 3y-2x=7, solve for x.

  • Math -

    I'll answer 2.

    to get rid of the y's we make this a simultaneous equation
    (1)4x-y=-9
    (2)3Y-2X=7
    the number of y's must be equal so that they will cancel eachother out when we add them together
    so 3*(1)=12x-3y=-27
    then we do (1)+(2)
    12x-3y+3y-2x=-27+7
    hopefully you will see that the y's cancel eachother out and we are left with
    10x=-20
    therefor x=-2

    if you are unsure with any of the steps feel free to ask :)

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