Systems Elimination and Word Problems

On Monday Joe bought 10 cups of coffee and 5 doughnuts for his office at the cost of $16.50.  On Tuesday he bought 5 cups of coffee and 10 doughnuts for a total of $14.25. Which equations could be used to determine the cost of the coffee?

• 10c + 5d = 14.25
  5c + 10d = 16.50

• 10c + 5d = 16.50
  5c + 10d = 14.25

• c + d = 10
  5c + 10d = 16.50

• c + d = 5
  5c + 10d = 16.50

Tags

CCSS.8.EE.C.8C

Homer sells tickets for admission to your school play and collects a total of $104. Admission prices are $6 for adults and $4 for children. He sold 21 tickets total. Solve the system:
x + y = 21
6x + 4y = 104

• (10, 11)

• (12, 9)

• (11, 10)

• (9, 12)

Tags

CCSS.8.EE.C.8C

 4x + 8y = 20
-4x + 2y = -30

• (-7,1)

• (2,-5)

• (-2,5)

• (7,-1)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Josh is thinking of two numbers. Their sum is -10 and their difference is -2. Which system of equations represents the situation?

• x - y = -10
  x + y = -2

• x = -2
  y = 5

• x + y = -2
  x - y = -10

• x + y = -10
  x - y = -2

Tags

CCSS.HSA.CED.A.3

Which of the following could be a correct first step in solving the system shown? Select all that apply.

• Multiply the first equation by 2, then add the result to the third equation.

• Multiply the second equation by 2, then add the result to the third equation.

• Add the first and second equation.

• Add the first and third equation.

• Add the second and third equation.

Solve using Elimination Method:

x - y = 11

2x + y = 19

• (10,-1)

• (-1,10)

• (3,-4)

• (6,7)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve using Elimination Method:

9x - 4y = 7

x - 4y = -17

• (-1,5)

• (-7,5)

• (7,5)

• (3,5)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve using Elimination Method:

4x + 9y = 28

-4x - y = -28

• (-7,0)

• (6,0)

• (-6,0)

• (7,0)

• (6,7)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve using Elimination Method:

4x+ 9y = 28

-4x -y = -28

• (-7,0)

• (6,0)

• (-6,0)

• (7,0)

• (6,7)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve by elimination:

7x - 9y = 29

7x + 2y = - 15

• (-4,-1)

• (-1.-4)

• (-1,4)

• (-1,6)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6