Give me instruction examples of how to use the three different ways to solve an system of linear equations

Substution- lStep 1: Solve one of the equations for either x = or y = . We will solve second equation for y. Step 2: Substitute the solution from step 1 into the second equation.Step 3: Solve this new equation.
3x+4y
6x+y

Emlination-The elimination method of solving systems of equations is also called the addition method. To solve a system of equations by elimination we transform the system such that one variable "cancels out". ... In order to solve for y, take the value for x and substitute it back into either one of the original equations.

3a+2y=15
-3a+3y= 15   you would elimination the 3a and -3a because they are opposites.
Graphing- To solve a system of equations graphically, graph both equations and see where they intersect. The intersection point is the solution. The slope-intercept method of graphing was used in this example. The point of intersection of the two lines, (3,0), is the solution to the system of equations.

Sorry thats a lot to read