Lesson System of equations helps to solve a problem for the Thanksgiving day

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System of equations helps to solve a problem for the Thanksgiving day


Problem 1

Kylie was buying pies at the store for her co-workers on Thanksgiving.  She needs a total of  12  pies.
The store sells pumpkin pies for  $4  a pie and apple pies for  $2  a pie.  If Kylie ended up spending $30 on pies alone,
how many of each pie did she purchased?

Solution

Let  x  represents the number of pumpkin pies that Kylie buys,  and let  y  represents the number of apple pies.

The total number of pies purchased is  x + y = 12.

The total cost is  4x + 2y = 30.


Thus you have this system of equations to solve:

 x +  y = 12,
4x + 2y = 30.


Solving the the first equation for y gives:

y = 12 - x


Substituting  "12 - x"  in place of  y  in the equation  4x + 2y = 30  gives:

4x + 2(12 - x) = 30,

4x + 24 - 2x = 30,

2x + 24 = 30,

2x = 6  ====>  x = 3.


Thus,  she has purchased 3 pumpkin pies,  and  12 - 3 = 9  apple pies.


Answer.  Kylie has purchased  3  pumpkin pies,  and  9  apple pies.


My other lessons in this site on solving systems of two linear equations in two unknowns  (Algebra-I curriculum)  are
    - Solution of the linear system of two equations in two unknowns by the Substitution method
    - Solution of the linear system of two equations in two unknowns by the Elimination method
    - Solution of the linear system of two equations in two unknowns using determinant
    - Geometric interpretation of the linear system of two equations in two unknowns
    - Useful tricks when solving systems of 2 equations in 2 unknowns by the Substitution method
    - Solving word problems using linear systems of two equations in two unknowns

    - Word problems that lead to a simple system of two equations in two unknowns
    - Oranges and grapefruits
    - Using systems of equations to solve problems on tickets
    - Three methods for solving standard (typical) problems on tickets
    - Using systems of equations to solve problems on shares
    - Using systems of equations to solve problems on investment
    - Two mechanics work on a car
    - The Robinson family and the Sanders family each used their sprinklers last summer
    - Roses and vilolets
    - Counting calories and grams of fat in combined food
    - A theater group made appearances in two cities
    - Exchange problems solved using systems of linear equations
    - Typical word problems on systems of 2 equations in 2 unknowns
    - HOW TO algebraize and solve these problems on 2 equations in 2 unknowns
    - One unusual problem to solve using system of two equations
    - Non-standard problem with a tricky setup
    - Sometimes one equation is enough to find two unknowns in a unique way
    - Solving mentally word problems on two equations in two unknowns
    - Solving systems of non-linear equations by reducing to linear ones
    - Solving word problems for 3 unknowns by reducing to equations in 2 unknowns
    - Using system of two equations to solve the problem for the day of April, 1

    - OVERVIEW of lessons on solving systems of two linear equations in two unknowns

Use this file/link  ALGEBRA-I - YOUR ONLINE TEXTBOOK  to navigate over all topics and lessons of the online textbook  ALGEBRA-I.


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