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27 August, 10:17

Joanna went school supply shopping. She spent $30.70 on notebooks and pencils. Notebooks cost $2.20 each and pencils cost $1.09 each. She bought a total of 19 notebooks and pencils. How many of each did she buy?

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  1. 27 August, 12:15
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    Ok, so we need to set up a system of equations.

    x + y = 19, where x is notebooks and y is pencils

    2.2x + 1.09y = 30.70. You use the coefficient for individual prices and the total for the total given.

    2.2x + 2.2y = 41.8 (multiply for elimination later)

    2.2x + 1.09y = 30.7

    1.11y = 11.1

    y = 11.1/1.11

    y = 10

    Now we use the substitution method in x + y = 19

    x + 10 = 19

    x = 9

    9 notebooks and 10 pencils
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