.
3y - 4x = 9,
-3y - 2x = 9.
Add the two equations and see what will happen.
This miracle is called the Elimination method.
On the Substitution method, Elimination method, Determinants' method for solving the systems of two linear equations
in two unknowns see the lessons
- Solution of the linear system of two equations in two unknowns by the Substitution method
- Solution of the linear system of two equations in two unknowns by the Elimination method
- Solution of the linear system of two equations in two unknowns using determinant
- Geometric interpretation of the linear system of two equations in two unknowns
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this online textbook under the topic "Systems of two linear equations in two unknowns".