In this optional lesson, students use the concepts they learned from the unit to get additional information in order to write linear equations and solve systems of equations. The focus is on the importance of slope and intercept in determining the number of solutions for a system, but students must also use their understanding of writing equivalent equations to find information about the lines.

The optional activity gives students an opportunity to demonstrate their understanding of the number of solutions in a system, by writing their own equation that would result in a system with a specified number of solutions.