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Math Help - Fast Application Help!!!

  1. #1
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    Fast Application Help!!!

    hi im in a hurry and i dont get a few problems please help...

    -The diffrence between two numbers is 16. Three times the larger number is nine times smaller. What are the numbers? Show some work if you can please....


    -A gardener has two kinds of solutions containing weed killer and water. One solution is 5% weed killer and the other solutiion is 15% weed killer. The gardener needs 100 liters of a 12% solution of weed killer and wants to make it by mixing it himself. How much of each solution should he use?

    THX FAST PLX!
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  2. #2
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    Problem 1
    Let x>y be the 2 numbers thus,
    x-y=16 (1)
    3x=9y (2)
    Divide equation (2) by 3 thus,
    x=3y
    Substitute that into equation (1) thus,
    3y-y=16
    Thus,
    2y=16
    Thus,
    y=8
    Thus,
    x=24
    Q.E.D.
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  3. #3
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    Problem 2:
    Let x,y be the amout of weedkiller solution for 5% and 15% respectively.
    Thus, he want to make 100 thus,
    x+y=100
    Now for the second part since the first solution has 5% the amount of actual weedkiller is .05x=\frac{1}{20}x similarily the amount of actual weekiller for the second one is .15y=\frac{3}{20}.
    Now he mixes them in such a way that he has 12% of weedkiller thus, there are
    12%(100) of actual weedkiller thus, 12. Thus, the two equations are:
    x+y=100
    \frac{1}{20}x+\frac{3}{20}y=12
    Multiply the second by 20 thus,
    x+y=100
    x+3y=240
    From the second subtract the first,
    2y=140
    Thus, y=70 of 15% solution.
    Thus, x=30 of 5% solution.
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  4. #4
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    I dont get how you got 1/20 and 3/20 for the equations....
    Quote Originally Posted by ThePerfectHacker
    Problem 2:
    Let x,y be the amout of weedkiller solution for 5% and 15% respectively.
    Thus, he want to make 100 thus,
    x+y=100
    Now for the second part since the first solution has 5% the amount of actual weedkiller is .05x=\frac{1}{20}x similarily the amount of actual weekiller for the second one is .15y=\frac{3}{20}.
    Now he mixes them in such a way that he has 12% of weedkiller thus, there are
    12%(100) of actual weedkiller thus, 12. Thus, the two equations are:
    x+y=100
    \frac{1}{20}x+\frac{3}{20}y=12
    Multiply the second by 20 thus,
    x+y=100
    x+3y=240
    From the second subtract the first,
    2y=140
    Thus, y=70 of 15% solution.
    Thus, x=30 of 5% solution.
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  5. #5
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    Quote Originally Posted by dvnswl
    I dont get how you got 1/20 and 3/20 for the equations....
    5%=5/100=1/20,

    so 1/20 th of the first solution is weedkiller.

    15%=15/100=3/20,

    so 3/20 ths of the second solution is weedkiller.

    RonL
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