One algebraic method is the substitution method. In this case, the value of one variable is expressed in terms of another variable and then substituted in the equation. In the other algebraic method – the elimination method – the equation is solved in terms of one unknown variable after the other variable has been eliminated by adding or subtracting the equations. For example, to solve:
8x + 6y = 16
-8x – 4y = -8
Using the elimination method, one would add the two equations as follows:
8x + 6y = 16
-8x – 4y = -8
2y = 8
y = 4
The variable “x” has been eliminated. Once the value for y is known, it is possible to solve for x by substituting the value for y in either equation:
8x + 6y = 16
8x + 6(4) = 16
8x + 24 = 16
8x + 24 – 24 = 16 – 24
8x = -8
X = - 1