###
GED Math Review: Solving Systems by Substitution

__Questions:__

**A. Solve each system by substitution. Check your answer.**

- x + y = 3

2x + 4y = 8

Solution: __________
- x + 2y = 7

4x + 3y = 3

Solution: __________
- -4x + y = 3

5x - 2y = -9

Solution: __________
- 8x - 7y = -2

-2x - 3y = 10

Solution: __________
- 2x - 2y = 5

4x - 4y = 9

Solution: __________
- 2x + 7y = 2

4x + 2y = -2

Solution: __________
- 2x - y = 7

2x + 7y = 31

Solution: __________
- x - 2y = -4

4y = 2x + 8

Solution: __________

**B. Tell whether it is more efficient to solve for x and then substitute for x or to solve for y and then substitute for y. Explain your reasoning. Then solve the system.**
- 9x - 3y = 15

x + 3y = -8

______________________________________

______________________________________

Solution: __________
- x/2 + y = 6

x/4 + y/2 = 3

______________________________________

______________________________________

Solution: __________

Answers:

- (2, 1)
- (-3, 5)
- (1, 7)
- (-2, -2)
- no solution
- (-3/4, 1/2)
- (5, 3)
- infinitely many solutions
- (1, -3)
- infinitely many solutions

Reference:

Complete Test Preparation for the GED Test 2014 by Steck-Vaughn