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Math Help - Writing equations help needed!! Test Tomorrow!!

  1. #1
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    Writing equations help needed!! Test Tomorrow!!

    'Kso, I have a math test tomorrow and I just stumbled across this question which I don't get. You have to write an equation for the problem and then solve it. Could I possibly get some help? It's urgent...

    The width of a rectangle is one third the length, the perimeter is 48cm. Find the length and width, how would I represent this as an equation and then solve it?
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  2. #2
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    Quote Originally Posted by BubblyCuppycake489 View Post
    'Kso, I have a math test tomorrow and I just stumbled across this question which I don't get. You have to write an equation for the problem and then solve it. Could I possibly get some help? It's urgent...

    The width of a rectangle is one third the length, the perimeter is 48cm. Find the length and width, how would I represent this as an equation and then solve it?
    If the length of the rectangle is 3 times as long as the width then:

     l = 3w

    You also know the perimeter. The permiter is the length of the outside of the rectable, which is made up of two straight lines the length of the width, and 2 straight lines the length of the length, hence:

     2l+2w = 48

    You now have 2 equations in 2 unknowns, and can solve.
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  3. #3
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    Talking

    If you're not yet familiar with systems of equations, you can just plug the "3w" from the first equation in for the "l" in the second equation:

    . . . . . 2(3w)\, +\, 2w\, =\, 48

    Solve for the value of "w", and then back-solve for the length.
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