1. Substitution

2. Take OUT the variable and PUT in the new expression
y = 4x + 1 2x – y = 9
y = -2x -3
y = 6x + 1
y = 4x + 1
2x – y = 9
y = -2x - 3
y = 6x +1
2x – (4x + 1) = 9
-2x – 3 = 6x + 1

3. Take OUT the variable and PUT in the new expression
y = 4x + 1 2x – 2y = 9
x = -2x -3
y = 6x + 1
y = 4x + 1
2x – 2y = 9
x= -2x - 3
y= 6x +1
2x – 2(4x + 1) = 9
y = 6(-2x – 3) + 1

4. Write the NEW equation after you substitute.
Your Turn!
Write the NEW equation after you substitute.

5. y = 6x – 11 -2x – 3y = -7
-2x – 3(6x-11) = -7

6. 2x – 3y =-1 y = x - 1
2x – 3(x-1) = -1

7. y = -3x +5 5x – 4y = -3
5x – 4(-3x + 5) = -3

8. (-5x-17) = -x – 1 or (-x – 1) = -5x - 17
y = -x -1 Y = -5x - 17
(-5x-17) = -x – 1 or (-x – 1) = -5x - 17

9. y = -2 4x – 3y = 18
4x – 3(-2) = 18

10. x= -2y x – 2y = -13
-7(-2y + 11) – 2y = -13

11. y = -5x – 21 y = 4x +6
(-5x - 21) = 4x + 6 or (4x + 6) = -5x - 21

12. y = 1/2x – 2 -5x + y = -2
-5x + (1/2x-2) = -2

13. x = -3y x – 3y = -15
-3(-3y + 1) – 3y = -15