An appropriate description of the Substitution Method would be

The substitution method is one of several methods used for solving systems of equations. If, for example, you have a system of two linear equations in x and y, you could solve either equation for x and subst. the resulting expression in y into the other equation. This eliminates x and allows you to find the value of y.

Example: Solve this system of linear equations:

3x + 4y = 7

2x + y = - 3

Let's solve the 2nd equation for y: y = - 2x - 3. Now substitute - 2x - 3 for y in the other equation: 3x + 4 (-2x-3) = 3 (Note how y disappears!)

Then 3x - 8x - 12 = 3; - 5x = 15 = > x=-3.

Again we substitute: Subst. - 3 for x in either of the given equations and solve for y.

Write your solution in the form (x, y).

These are examples of the subst. method and its applications.