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Directions: Show all of your work for the following two problems on a seperate sheet of paper. Take a picture of your work and attach the picture to this assignment.

1. Solve the following system of equations, show all your work on a separate sheet of paper, and check your answer. Write the solution as a point (x,y) (4 points).

3x + 5y = -40

–x + 4y = -15?



2. Suppose you and your friends form a band and you want to record a demo. Studio A rents for $125 plus $50 an hour and Studio B rents for $200 and $30 an hour. Let t = the number of hours and c = cost.

Write an equation to represent the cost at each studio (2 points)

Solve the system (2 points)

Write the solution as a point (x, y) (2 points)

Respuesta :

kadambarisures

Answer:

x = -5  y = -5

Step-by-step explanation:

–x + 4y = -15

     - 4y  -4y

-1(-x = -4y - 15)

x = 4y + 15

Substitute x = 4y + 15 into 3x + 5y = -40

3(4y + 15) = -40

17y + 45 = -40

      - 45   -45

17y = -85

/ 17    /17

y= -5

Substitute y = - 5 into x = 4y + 15:

x = 4(-5) + 15

x = -20 + 15

x = -5

Answer:

Part I

(-5,-5)

Part II

(3.75, 312.50)

Step-by-step explanation:

Part I

(1) 3x + 5y = -40

(2) -x + 4y = -15

solve for x in (2)

x = 15 + 4y

substitute into (1)

3(15+4y) + 5y = -40

45 +12y + 5y = -40

45 +17y = -40

17y = -85

y = -5

substitute y = -5 into (1)

3x + 5(-5) = -40

3x -25 = -40

3x = -15

x = -5

so  (-5, -5)

Part II

Studio A  

C = 125 + 50t

Studio B

C = 200 + 30t

125 + 50t = 200 + 30t

20t = 75

t = 3.75

(3.75, 312.50)

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