Intermediate Algebra help

  1. i have this algebra question where i have to combine 15% of a solution with 45% of a solution to form 300ml of a 35% solution. i read examples over and over again, and did the problem over and over again. can anyone provide a helpful technique. i know it is probaly a very simple question for you all but i can't take it anymore, math is my weakness and i need help


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  2. 30 Comments

  3. by   meandragonbrett
    My honors calculus teacher taught us a really easy way to do them....but I can't explain it over the net. Sorry I can't help you. Search the net some...you might be able to find it explained a different way and it might click.
    Good Luck!
    Brett
  4. by   adrienurse
    I'm having algebra problems too. It's been 10 years since I've done this sh*t and I can't remember how to isolate variables or the order of operations. Anybody know any good tutorial sites. Anyone want to tutor me?
  5. by   SirJohnny
    SOLUTION: "SYSTEM OF EQUATIONS" PROBLEM <-- LOOK FOR THIS IN INDEX OF YOUR ALGEBRA TEXT

    STEP 1: SETUP THE EQUATIONS:
    (0.15)X + (0.45)Y = 300(0.35) [TOP EQUATION]
    X + Y = 300 [BOT EQUATION]

    STEP 2: SIMPLIFY TOP EQUATION:
    (0.15)X + (0.45)Y = 105 [TOP EQUATION]
    DO NOTHING WITH BOT EQUATION: X + Y = 300 [BOT EQUATION]

    STEP 3: DIVIDE TOP EQUATION BY (0.15)
    X + 3Y = 700 [TOP EQUATION]
    DO NOTHING WITH BOT EQUATION: X + Y = 300 [BOT EQUATION]

    STEP 4: MULTIPLE TOP EQUATION BY (-1)
    -X + -3Y = -700 [TOP EQUATION]
    DO NOTHING WITH BOT EQUATION: X + Y = 300 [BOT EQUATION]

    STEP 5: ADD TOP AND BOT EQUATION TOGETHER:
    -2Y = -400

    STEP 6: DIVIDE BOTH SIDES BY (-2)
    Y = 200

    STEP 7: SUBSTITUTE "Y=200" INTO EITHER THE BOT OR TOP EQUATION. DOES NOT MATTER WHICH EQUATION YOU USE. I SHOW BOTH JUST AS AN EXERCISE.

    [TOP EQUATION]
    (0.15)X + (0.45)200 = 300(0.35)
    (0.15)X + 90 = 105
    (0.15)X = 105 - 90
    (0.15)X = 15
    X = 100

    [BOT EQUATION]
    X + 200 = 300
    X = 300 - 200
    X = 100

    STEP 8: PROVE BY LETTING X = 100 & Y = 200 AND SUBSTITUTING INTO EITHER TOP OR BOT EQUATION.

    [TOP EQUATION]
    (0.15)100 + (0.45)200 = 300(0.35)
    15 + 90 = 105
    105 = 105 ** IMPORTANT THAT BOTH SIDES ARE SAME ***


    STEP 9: WRITEUP YOUR ANSWER:

    YOU NEED 100ml of solution X which is a 15% solution.
    YOU NEED 200ml of solution Y which is a 45% solution.

    ADD THESE TOGETHER AND YOU GET 300ml of solution Z which is a 35% solution.

    ===============

    John Coxey
    (jpcoxey@aol.com)

    MS-COMPUTER SCIENCE ---> LOOKING TO BECOME RN SOMEDAY I HOPE!!!!
    Last edit by SirJohnny on Jan 30, '03
  6. by   SirJohnny
    Sorry - could not get equations to line up.

    Cut and paste into NotePad. Use CourierNew font so text
    will line up. Can't do with default TimesRoman.

    Then manually line up the TOP & BOT equations for each
    step and things will be much clearer.

    ----------------

    Whenever you get a word problem. Trick is to try to see how
    to make it fit into the general equations for the section you
    are working on.

    If you are doing regular math problems for that section, then
    try to make the word problems fit into the regular math problems.

    A bear, I know.

    I took Calculus 5 times - but ended up with a BS-Applied Mathematics and finally an MS-Computer Science.

    Am working in computer industry - but want to pursue career in nursing.

    John Coxey
    (jpcoxey@aol.com)
  7. by   MishlB
    http://mathforum.org/dr.math/

    Works every time!!!!!!!!!
  8. by   Mkue
    wow, where were you guys when I took algebra??? lol.. great info.
  9. by   Sally_ICURN
    John you boggle my mind!! My daughter is currently in a doctoral program at UC San Deigo. Her area is math. She teaches undergrad as well as completing her own studies--she's only 24! I was chatting with her online just now and was going to ask her the question. I have a ton of respect for people who can explain math...period! Great minds!!

    ~Sally
  10. by   melissa24
    John Coxey...

    You rock!
  11. by   passing thru
    IMPRESSIVE ! JOHN !
  12. by   NRSKarenRN
    John, can you tutor me in statistics in exchange for nursing knowledge???
  13. by   adrienurse
    Okay people. Here's one that I'm stuck on.

    formula is:
    z=(a-b)/c

    z=-1.5
    a=75
    c=10
    What is b?

    Making my head hurt just thinking about it.
  14. by   ava'smomRN
    Thanks John Coxey
    i understand r explanation than the book but i hope this problem will not be on my test!!!

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