Ask Me Help Desk

Ask Me Help Desk (https://www.askmehelpdesk.com/forum.php)
-   Mathematics (https://www.askmehelpdesk.com/forumdisplay.php?f=199)
-   -   Elimination or substitution Equation2 (https://www.askmehelpdesk.com/showthread.php?t=198533)

  • Mar 25, 2008, 12:32 PM
    floree
    Elimination or substitution Equation2
    Employees of an office ordered lunch from a local store, One day the order was for 4 hamburgers and 3 orders of fries, a total cost of $24. Another day, the order was for 6 hamburgers and l order of fries, for a total cost of $29. Set up equation and solve by elimination or substitution.

    My equations are : 4h +3f=24 and 6h+1f+29 is this correct?
  • Mar 25, 2008, 01:22 PM
    Credendovidis
    Quote:

    Originally Posted by floree
    Employees of an office ordered lunch from a local store, One day the order was for 4 hamburgers and 3 orders of fries, a total cost of $24. Another day, the order was for 6 hamburgers and l order of fries, for a total cost of $29. Set up equation and solve by elimination or substitution.

    My equations are : 4h +3f=24 and 6h+1f+29 is this correct?

    No. Almost correct. It is : 4h +3f=24 (1) and 6h+1f = 29 (2)

    Additional
    Solution for f :
    (1) all parts times 3 :
    (2) all parts times 2 :
    (1) 12h + 9f = 72
    (2) 12h + 2f = 58
    -------------------- -
    --- 00h + 7f = 14
    7f = 14 --> 1f = 14/7 --> 1f = 2

    And solution for h :
    4h + 3f = 24
    4h + 6 = 24
    4h = 24 - 6 = 18
    1h = 18/4 = 4,50 --> 1h = 4,50
  • Apr 1, 2008, 06:32 PM
    confusedbuzz
    Quote:

    Originally Posted by floree
    My equations are : 4h +3f=24 and 6h+1f+29 is this correct?


    The first equation is right but the second one should be : 6h+1f=29 because 29 is the total cost. Solving them simultaneously through elimination can be done like this:

    4h + 3f = 24
    6h + 1f = 29

    -4h - 3f = -24
    18h + 3f = 87

    - 4h + 18h = -24 + 87

    14h = 63
    h = 63/14 = 4.5

    4(4.5) +3f = 24
    f = (24-18)/3 = 6/3 = 2

    h = 4.5, f = 2

    You'll see that using substitution will give you the same answer. If you want to do it through substitution, this is how to do it:

    4h + 3f = 24
    6h + f = 29

    f = 29 - 6h

    4h + 3(29-6h) = 24
    4h + 87 - 18h = 24

    And we are left with the same single equation we saw before in the elimination method. Solving completely will get you the same answer.
  • Apr 2, 2008, 05:48 AM
    Credendovidis
    Quote:

    Originally Posted by floree
    Employees of an office ordered lunch from a local store, One day the order was for 4 hamburgers and 3 orders of fries, a total cost of $24. Another day, the order was for 6 hamburgers and l order of fries, for a total cost of $29. Set up equation and solve by elimination or substitution.

    My equations are : 4h +3f=24 and 6h+1f+29 is this correct?

    A reaction to an answer is always much appreciated, even if it does not solve your specific problem...
    :)

  • All times are GMT -7. The time now is 11:40 AM.