Math help: 2x+6y=300,3x+5y=350, what is x and y?

I have no idea how to do problems like these, so if you can please give me the steps on how to do this also? :(

3 Answers

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  • iceman
    Lv 7
    9 years ago
    Favorite Answer

    2x+6y=300

    3x+5y=350

    -6x-18y=-900

    6x+10y= 700

    -8y = - 200

    y = 25

    x = 75

  • Anonymous
    9 years ago

    set them up right on top of eachother so that all the like terms are directly over the other:

    2x + 6y = 300

    3x + 5y = 350

    First you want to get rid of one of the variables. You can pick either one; I'm going to pick x.

    You will get rid of x by multiply the top and bottom by a number that will cancel eachother out. (for example, you'd want x to be 2 on the top and -2 on the bottom because 2-2 = 0)

    So, multiply the entire top function by -3 because the coefficent of x on the bottom is 3: -3(2x + 6y = 300) = -6x - 18y = -900

    Then, multiply the entire bottom function by 2. 2(3x + 5y = 350) = 6x + 10y = 700

    Now set them up on top of each other again:

    -6x - 18y = -900

    6x + 10y = 700

    Now you can add the like terms together from top to bottom.

    -6x + 6x = 0 ; -18y + 10y = -8y ; -900 + 700 = -200

    you are left with -8y = -200

    now solve for y. -200/-8 = 25

    y = 25

    Now, to find x, all you do is plug in 25 for one of the given functions.

    2x + 6y = 300

    2x + 6(25) = 300

    2x + 150 = 300

    2x = 150

    x = 150/2

    x = 75

    Now plug in the x and y values you got to check your work.

    2(75) + 6(25) = 300

    it does work so your answers are

    x = 75 y = 25

  • 9 years ago

    You can use substitution or elimination. Substitution would be easiest in this problem.

    You need to get one variable alone on one side of one of the equations. I will use the first one because it's easier.

    2x + 6y = 300

    x+3y=150

    x=150-3y

    Then plug in what you get for x, into the other equation where x is.

    3x+5y=350

    3(150-3y) + 5y = 350

    450 - 9y + 5y = 350

    450 - 4y= 350

    -4y = -100

    y=25

    Then you plug in y, to find x.

    2x + 6(25) = 300

    2x + 150 = 300

    2x = 150

    x= 75

    x=75 and y=25

    You can plug both x and y into each equation and it should work out.

    Hope this helps :) :) :)

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