Mark bought 12 boxes of paper clips and 10 packages of index cards for a total cost of $61.70. Janice bought 15 boxes of paper clips a

Question

Mark bought 12 boxes of paper clips and 10 packages of index cards for a
total cost of $61.70. Janice bought 15 boxes of paper clips and 7 packages of
index cards for a total cost of $55.40. Find the cost of one box of paper clips
and the cost of one package of index cards.

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Khánh Gia 3 months 2021-07-24T14:10:34+00:00 1 Answers 6 views 0

Answers ( )

    0
    2021-07-24T14:12:17+00:00

    Answer:

    paper clips = $1.85

    index cards = $3.95

    Step-by-step explanation:

    Mark

    12 paper clips = x

    10 index cards = y

    $61.70 total

    Janice

    15 paper clips = x

    7 index cards = y

    $55.40 total

    12x + 10y = 61.70

    15x + 7y   = 55.40

    *** you want to cancel out one of the letters

    (12x + 10y = 61.70) * -7

    (15x + 7y   = 55.40) * 10

    -84x -70y = -431.9

    150x + 70y = 554.0

    150x + 70y = 554.0

    -84x -70y = -431.9

    66x + 0 = 122.1

    66x = 122.1

    x = 122.1 ÷ 66

    x = 1.85

    plug it back in

    15(1.85) + 7y   = 55.40

    27.75 + 7y   = 55.40

    7y   = 55.40 – 27.75

    7y = 27.65

    y = 27.65 ÷ 7

    y = 3.95

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