This document discusses linear systems and methods for solving them. A linear system is a set of linear equations where a solution is an ordered pair that satisfies both equations. Graphically, the solution is the point where the lines intersect. Systems can have one solution, infinitely many solutions if the lines are the same, or no solution if the lines are parallel. The document presents two methods for algebraically solving systems: substitution and elimination. Substitution involves solving one equation for a variable and substituting it into the other equation. Elimination involves adding or subtracting equations to eliminate a variable.