Solving a system of equations graphically is simple. Find the place where the two lines intersect and this is the solution to the system. This is because the point (or points) where the two lines meet is on both lines. So, this point satisfies both equations.
For example, in "Paying the Plumber," your two lines intersected when the plumbers worked for 3 hours and charged you $150. This point was the only point where both companies would charge you exactly the same amount of money for the same amount of work.
The point (3, 150) is a point on both lines and it satisfies both equations.
The solution to this system of equations is (3, 150).
Open a new Excel document. Create a table for the situation on the left. Use the information in the situation (the story) to complete the table. Create a graph in Excel. (If you get stuck, go back and watch the video on "Graphing in Excel."). Title your graph, "Computer Sales" 

Attach the Excel document with the table and graph below to an email. Copy and paste the questions below into your email. 
For the subject of your email, type Computer Sales .
1. Use your graph for the Computer Sales to answer these questions:
a. How many computers do you have to sell to make the same amount of money for both companies?
b. What is the solution to this system of equations?
2. Look back at your answer to Activity 1: Comparing Cell Phone Plans.
a. At what time, will the two companies charge you the same amount of money?
b. What is the solution to this system of equations?
Activity 2: Interactive Horizontal and Vertical Systems of Equations
Activity 3: Systems Graphing Calculator
Site Map: Home>Algebra Units>Systems of Equations>Solving Graphically
Activity 1: Solving Systems of Equations by Graphing