- Example of two variables one degree equation
- Question:
- Given: x + 3y = 9 ...equation1
- and 3x + 6 = 15 ...equation2
- solve for x and y.

- Solution:
- because the equation2 has only one variable x, so we solve equation2 first to get the value of x.
- 3x + 6 = 15
- move the number to the right side of the equation
- 3x = -6 + 15 = 9
- x = 9/3 = 3
- substitute x = 3 into equation1
- x + 3y = 9
- 3 + 3y = 9
- 3y = 9 - 3 = 6
- y = 6/3 = 2
- so the solution is x = 3 and y = 2

Use the substitution method to solve the two variables equations. Because the equation2 has only one variable x, make the equation2 into the standard form ax = b. the value of x is b/a. Substitute the value os x into equation1 to get an equation which has only varianle y. make the equation into the standard form cy = d, then y = d/c. Check if the valurs of x and y satisfy original equations.