The Substitution Method of Solving Systems of Equations-Solve one of the equations for one of its variables. Then substitute the expression from the first thing you did into the other equation and solve fort he other variable. Then substitute the value from that equation into the revised equation from the first thing you did and solve.

3x+4y=-4
x+2y=2

1. Solve equation 2 for x.
x+2y=2
x=-2y+2

2.Substitute the expression for x into Equation 1 and solve for y.
3x+4y=-4
3(-2y+2)+4y=-4
y=5

3.Substitute the value of y into revised Equation 2 and solve for x.
x=-2y+2
x=-2(5)+2
x=-8

4. The solution is (-8,5).

The Combination Method of Solving Systems of Equations- Multiply one or both of the equations by a constant to obtain coefficients that differ only in sign for one of the variables. Next add the revised equations from the first thing you did. Combining like terms will eliminate one of the variables. Solve for the remaining variable. Then substitute the value obtained in the second step into either of the original equations and solve for the other variable.

2x-4y=13
4x-5y=8

1.Multiply the first equation by -2 so that the x-coefficients differ only in sign.
2x-4y=13 *-2 -4x+8y=-26
4x-5y=8 *1 4x-5y=8

2. Add the revised equations and solve for y.
3y=-18
y=-6

3. Substitute the value of y into one of the original equation. Solve for x.
2x-4y=13
2x-4(-6)=13
2x+24=13
x=-11/2

4. The solution is (-11/2, -6).

The Graphin Method of Solving Systems of Equations- Graph both equations. Then look where the lines intersect. The intersection will be the solution.

2x-3y=-2
4x+y=24

1. Graph both equations as lines.

2. Find the intersection of the lines, this will be the solution of the system.
(5,4)