Solving a system of equations-Section 3.1-3.2 in College Alg
Solving a system of equations.
For video on this topic see
https://www.khanacademy.org/math/algebra/systems-of-eq-and-ineq/fast-systems-of-equations/v/solving-linear-systems-by-substitution
or http://patrickjmt.com/solving-a-linear-system-of-equations-by-graphing/
or http://patrickjmt.com/solving-a-linear-system-of-equations-using-substitution/
or http://patrickjmt.com/solving-a-linear-system-of-equations-using-elimination-by-addition/