Results 1 to 4 of 4

Math Help - linear equations in 2 variables....help please

  1. #1
    Newbie
    Joined
    Jun 2010
    Posts
    2

    linear equations in 2 variables....help please

    Translate into a pair of linear equations in two variables.
    solve the equations using elimination or substitution
    state your answer for specified variable


    Mrs. Boyd has a desk full of quarters and nickels. if she has a total of 25 coins with a total face value of 2.85 , how many are nickels?



    I have not been able to figure out how to do this problem and have tried.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    earboth's Avatar
    Joined
    Jan 2006
    From
    Germany
    Posts
    5,830
    Thanks
    123
    Quote Originally Posted by southrngrl1966 View Post
    Translate into a pair of linear equations in two variables.
    solve the equations using elimination or substitution
    state your answer for specified variable


    Mrs. Boyd has a desk full of quarters and nickels. if she has a total of 25 coins with a total face value of 2.85 , how many are nickels?



    I have not been able to figure out how to do this problem and have tried.
    1. Let x denote the number of quarters and y the number nickels.

    2. Then you know:

    \left|\begin{array}{rcl}x+y&=&25 \\ 0.25 \cdot x + 0.05 \cdot y&=& 2.85\end{array}\right.

    3. Solve for x and y.
    Last edited by earboth; June 20th 2010 at 08:59 AM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor Unknown008's Avatar
    Joined
    May 2010
    From
    Mauritius
    Posts
    1,260
    Let the number quarters be represented by q, and nickels by n.

    The total number of coins is q + n, which is equal to 25.

    So, you have

    q + n = 25

    Now, the value of a nickel is 5 and that of a quarter is 25 (I'm not sure for the value of a nickel, correct me if I'm wrong, it's not my currency).

    0.25q gives the value of the total quarters, and 0.05n gives the value of the total nickels.

    Their value add up to 2.85.

    So,

    0.25q + 0.05n = 2.85

    You now have:

    q + n = 25
    0.25q + 0.05n = 2.85

    Solve them simultaneously

    Post what you get!

    EDIT: Oops, didn't know you posted before me earboth
    Last edited by Unknown008; June 10th 2010 at 12:21 PM. Reason: Time delay...
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Jun 2010
    Posts
    2
    Thank you for the help. Now I will be ableto finish this. I had the first part but was not sure if it was right.

    THanks again. have a great week
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: April 20th 2010, 04:26 PM
  2. Linear Equations in two variables
    Posted in the Algebra Forum
    Replies: 1
    Last Post: December 30th 2008, 01:16 PM
  3. Linear equations in two variables add. help
    Posted in the Algebra Forum
    Replies: 2
    Last Post: May 26th 2008, 08:14 AM
  4. Linear equations in two variables
    Posted in the Algebra Forum
    Replies: 5
    Last Post: May 25th 2008, 11:58 AM
  5. Linear Equations in 4 variables..
    Posted in the Advanced Algebra Forum
    Replies: 6
    Last Post: September 25th 2007, 07:35 PM

Search Tags


/mathhelpforum @mathhelpforum