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mrs. page needed two types of paper for her art class. the premium color paper costs $40 per case and the plain white paper costs $30 per case. if she bought 20 cases all together and spent $720 total, how many cases of plain white paper did she buy?

Respuesta :

Mrs. Page bought 8 cases of plain white paper.

To solve for the number of cases of plain white paper Mrs. Page bought, we will use algebraic expressions.

Algebraic expression is an expression consisting variables ad coefficient.

We will designate a variable for the unknown and solve it using the algebraic expressions made.

The number of cases of plain white paper and premium color paper is unknown.

Let x = number of cases of plain white paper

and y = number of cases of premium color paper

If Mrs. Page bought 20 cases altogether, then

x + y = 20

If Mrs. Page spent a total of $720 for the 20 cases, and the premium color paper costs $40 per case and the plain white paper costs $30 per case, then:

30x + 40y = 720

Multiplying the first equation by 30, we get:

30x + 30y = 600

Subtracting it to the 2nd equation,

30x + 40y = 720

- 30x + 30y = 600

            10y = 120

y = 12

Recall that x + y = 20. Then,

x + 12 = 20

x = 8

Hence, Mrs. Page bought 8 cases of plain white paper and 12 cases of premium color paper.

To learn more about solving word problems using algebraic expressions: https://brainly.com/question/12470265

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