This Problem Set is a part of the Lesson 14, Unit 4, Grade 8. Students graph linear equations in standard form, that produce a horizontal or a vertical line. The goal of this lesson is for students to know that the graph of an equation in the form of x = c or y = c, where c is a constant, is the graph of a vertical or horizontal line, respectively. In order to show this, the lesson begins with linear equations in two variables, where one of the coefficients is equal to zero.