# Solving System of Equations by Addition or Subtraction

Objective: I know how to solve system of linear equations by addition or subtraction.

If the coefficients of one of the variables are opposites then the two equations are added together to eliminate one of the variables.

If the coefficients of one of the variables are equal then the two equations are subtracted from one another to eliminate one of the variables.

Look up the lesson on Solving System of Equations if you need help on solving system of equations.

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
Solve each equation.

- 4x - 5y = 9
- 4x + 4y = - 72
Answer: x = , y =

4x + y = - 13
- 4x - 4y = 16
Answer: x = , y =

3x + y = 18
3x + 4y = 36
Answer: x = , y =

4x - 2y = - 54
4x - y = - 45
Answer: x = , y =

- 2x - 3y = - 13
- 2x + 3y = 29
Answer: x = , y =

3x + 2y = 38
x + 2y = 26
Answer: x = , y =

- 5x + 4y = - 24
- x + 4y = - 24
Answer: x = , y =

x + 2y = 7
x + y = 6
Answer: x = , y =

4x - 5y = - 15
3x + 5y = 15
Answer: x = , y =

- 4x + 5y = 9
4x + 3y = 31
Answer: x = , y =

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