3x-4y =9
-3x+4y=12
add them
0 = 21
contradiction! so there is no solution
actually what you have are the equations of two parallel lines, which of course cannot intersect
To solve this system of equations, you can use the method of elimination.
The goal is to eliminate one variable by adding or subtracting the equations. In this case, the "x" terms will eliminate each other if we add the two equations together.
Adding the equations:
(3x - 4y) + (-3x + 4y) = 9 + 12
(-3x + 3x) + (-4y + 4y) = 21
0 + 0 = 21
As a result, we obtain the equation 0 = 21. However, this equation is not true, which means that the system of equations is inconsistent and does not have a solution.
In summary, the given system of equations has no solution.