Math Help!

1.) Solve the system by graphing. You may use paper or a calculator.

2x - y = 8

x + 3y = 11

2.) The revenue for a certain brand of toothpaste is y = 2.5x where 'x' is the number of tubes of toothpaste sold and 'y' is the total income for selling 'x' tubes. The cost equation is y = 0.9x + 3000, where 'x' is the number of tubes manufactured and 'y' is the cost of producing 'x' tubes. Find the value of 'x' where the company breaks even.

x=?

Please help, thank you!

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  1. 1.)

    Plot a Cartesian coordinate system

    1 equation :

    For x = 0

    - y = 8 Multiply both sides by - 1

    y = - 8

    For y = 0

    2 x = 8 Divide both sides by 2

    x = 4

    Mark points ( 0 , - 8 )

    x = 0 , y = -8

    and ( 4 , 0 )

    x = 4 , y = 0

    and draw line

    2 equation:

    For x = 0

    3 y = 11 Divide both sides by 3

    y = 11 / 3 = 3.67

    For y = 0

    x = 11

    Mark points ( 0, 3.67 )

    x = 0 , y = 3.67

    and ( 11 , 0 )

    x = 11 , y = 0

    and draw line

    Intersection of this two lines is solution of system.

    x = 5 , y = 2

    OR

    2 x - y = 8

    y = 2 x - 8

    x + 3y = 11

    y = ( 11 - x ) / 3

    in google type :

    functions graphs online

    When you see list of resulrt click on :

    Draw Function Graphs - Plotter - Rechneronline

    When page be open in blue rectangle type:

    2 x -8

    in gray rectangle type:

    ( 11 - x ) / 3

    In options :

    Range x-axis from set :

    - 3 to 7

    Range y-axis from set:

    - 15 to 5

    and click option draw

    2.)

    2.5 x = 0.9 x + 3000 Subtract 0.9 to both sides

    2.5 x - 0 . 9 = 0.9 x + 3000 - 0.9

    1.6 x = 3000 Divide both sides by 1.6

    x = 3000 / 1.6 = 1875

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  2. 0.9(7x+5)=1.6-(x-3)

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