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15 July, 00:33

Make an equation and solve!

A man has $0.70 in dimes and nickels. He has 8 coins altogether. How many nickels does he have?

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Answers (2)
  1. 15 July, 00:56
    0
    The number of nickels he has is 2.

    Step-by-step explanation:

    A man has $0.70 consisting of dimes and nickels. He has 8 coin altogether. The number of nickel he has can be calculated below.

    let

    number of dimes = a

    number of nickel = b

    a + b = 8 ... (i)

    Total cost

    1 dime = $0.1

    1 nickel = $0.05

    0.1a + 0.05b = 0.70 ... (ii)

    a + b = 8 ... (i)

    0.1a + 0.05b = 0.70 ... (ii)

    a = 8 - b

    insert the value of a in equation (ii)

    0.1 (8 - b) + 0.05b = 0.70 ... (ii)

    0.8 - 0.1b + 0.05b = 0.70

    0.80 - 0.70 = 0.1b - 0.05b

    0.1 = 0.05b

    divide both sides by 0.05

    b = 0.1/0.05

    b = 2

    Insert the value of b in equation (i)

    a + b = 8 ... (i)

    a + 2 = 8

    a = 8 - 2

    a = 6

    The number of nickels he has is 2.
  2. 15 July, 01:27
    0
    Answer: He has 6 dimes and 2 nickels.

    Step-by-step explanation:

    If D is the number of dimes and N the number of nickels, we have that:

    He has 8 coins:

    D + N = 8

    He has $0.70 in total:

    D*0.10 + N*0.05 = 0.70

    Then we have two equations, now we need to isolate one variable in one of the equations and then replace it in the other, let's isolate D in the first equation:

    D = 8 - N

    Now we can replace it in the other equation:

    (8 - N) * 0.10 + N*0.05 = 0.70

    0.80 - N * (0.10 - 0.05) = 0.70

    -N*0.05 = 0.70 - 0.80 = - 0.10

    N = 0.10/0.05 = 2

    D = 8 - N = 8 - 2 = 6

    He has 6 dimes and 2 nickels.
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