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algebra problem"Find the number of coins and their denomination?

A sum of money amounting to $20 consists of nickels dimes, and quarters. There are ten times as many dimes as quarters ,

and the number of nickels exceed twice the number of dimes and quarters by 24. FIND the number of coins of each denomination?

2 Answers

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  • Melvyn
    Lv 7
    7 years ago

    (0.05)n+ (0.1)d + (0.25)q= 20 where n = number of nickels , d = number of dimes and q = number of quarters

    d= 10 q

    n= 2(d+q) +24 - > n=2d+2q+24 -> n = 22q+24

    (.05) (22q+24) + q + q/4 = 20

    5 (22q+24) +100q+25q = 2000

    110q +120 +125q = 2000

    235q=1880

    q= 1880/235 = 8

    d = 10q=80

    n = 22 *8 +24 = 200

    check : 8 /4 +8 + 10 = 20 ...correct

  • 7 years ago

    Let N, D and Q be the number of nickels, dimes and quarters respectively.

    Now you just need to write the appropriate equations and solve:

    A sum of money amounting to $20 consists of nickels dimes, and quarters.

    If you take each coin times its value, you get the total value. Let's do this in cents, to make it simpler:

    5N + 10D + 25Q = 2000

    There are ten times as many dimes as quarters.

    Stated another way, the number of dimes is ten times the number of quarters.

    D = 10Q

    The number of nickels exceed twice the number of dimes and quarters by 24.

    N = 2(D+Q) + 24

    Let's substitute D = 10Q into the other two equations:

    5N + 10(10Q) + 25Q = 2000

    N = 2(10Q + Q) + 24

    Simplify the second equation:

    N = 2(11Q) + 24

    N = 22Q + 24

    Substitute this into the first equation:

    5(22Q + 24) + 10(10Q) + 25Q = 2000

    110Q + 120 + 100Q + 25Q = 2000

    Group terms:

    (110Q + 100Q + 25Q) + 120 = 2000

    235Q + 120 = 2000

    235Q = 2000 - 120

    235Q = 1880

    Q = 1880/235

    Q = 8

    Now solve for the other values:

    D = 10Q

    D = 10(8)

    D = 80

    N = 22Q + 24

    N = 22(8) + 24

    N = 176 + 24

    N = 200

    Answer:

    200 nickels, 80 dimes, 8 quarters

    Double-checking:

    Total value is $10 + $8 + $2 = $20

    There are ten times as many dimes as quarters (80 dimes, 8 quarters)

    The number of nickels (200) exceeds twice the number of dimes and quarters (88) by 24. Two times 88 = 176. Add 24 and you get 200.

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