Math

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A collection of 30 coins worth $5.50 consists of nickels, dimes, and quarters. There are twice as many dimes as nickels. How many quarters are there?

  • Math -

    Let the number of nickels be N
    let the number of dimes be D, so D = 2N
    let the number of quarters be Q
    but Q would then be 30-N-D
    = 30 - N - 2N
    = 30 - 3N

    now form an equation using the "value" of those coins:
    5(N) + 10(2N) + 25(30-3N) = 550

    solve for N, then backsubstitute for the others.
    Let me know what you got.

  • Math -

    so i did...
    5n+10(2n)+750-75n=550
    5n+20n-75n=-200
    -50n=-200
    n=4


    four nickels
    eight dimes
    12 quarters

    .. that's not right! D:

  • Math -

    4 nickels
    8 dimes, and
    30-4-8 = 18 quarters, (how did you get 12?)

    check: 4(5) + 8(10 + 18(25) = 550

  • Math -

    ohh!
    for some reason i multiplied 4 and three to get 12 quarters..

    wow silly mistake!

    thanks so much for the help!!

  • Math -

    fuch et just guess

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