Results 1 to 3 of 3

Math Help - A is two-third of the sum of B and C. B is three-quarter of the sum of A and C.

  1. #1
    Newbie
    Joined
    Aug 2009
    Posts
    15

    Exclamation A is two-third of the sum of B and C. B is three-quarter of the sum of A and C.

    A is two-third of the sum of B and C. B is three-quarter of the sum of A and C. Express A as a fraction of B.
    Last edited by mr fantastic; June 7th 2010 at 04:49 AM. Reason: Re-titled.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Grandad's Avatar
    Joined
    Dec 2008
    From
    South Coast of England
    Posts
    2,570
    Thanks
    1

    Simultaneous equations

    Hello dtay

    Welcome to Math Help Forum!
    Quote Originally Posted by dtay View Post
    A is two-third of the sum of B and C. B is three-quarter of the sum of A and C. Express A as a fraction of B.
    You need to create two equations involving A, B and C, and then eliminate C to find an equation involving just A and B.

    Here are some clues:

    The first statement can be written: A = \tfrac23(B+C)

    So if we multiply by 3: 3A = 2B+2C

    \Rightarrow C = \tfrac32A - B (1)

    Now write down the second statement in a similar way, and use equation (1) to eliminate C.

    Then re-arrange so that you have A on one side, and B on the other. Finally, divide both sides by B to find \frac{A}{B}. I get the answer:

    \frac{A}{B}= \frac{14}{15}

    Can you fill in the gaps?

    Grandad
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Aug 2009
    Posts
    15

    Smile

    Thank You very much, Grandad.
    I understand it already, and i also have found out another method, using
    common ratio.
    I'm sorry i wasn't able to thank you earlier.
    Thank you very much for helping me!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Filling the quarter plane with numbers
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: March 14th 2011, 12:59 AM
  2. quarter cirlces
    Posted in the Geometry Forum
    Replies: 12
    Last Post: June 24th 2010, 12:30 PM
  3. Volume of Rotation of a Quarter Circle
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 3rd 2010, 03:58 AM
  4. Nearest Quarter Hour
    Posted in the Algebra Forum
    Replies: 1
    Last Post: June 30th 2008, 09:22 AM
  5. Help with Probability flipping a quarter!!!!
    Posted in the Statistics Forum
    Replies: 6
    Last Post: February 26th 2008, 08:02 PM

Search Tags


/mathhelpforum @mathhelpforum