1. Solving a System of Equations
by Substitution
Step 1 _______ one variable.
Step 2 _______ that expression into the second equation.
Step 3
_______ for the variable.
Step 4
_______ the value into one of the original equations.
Step 5
_______ for the remaining variable. 7
4x - y = 0
x - 2y = -7
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia Adapted from various sources (MCC9-12.A.REI.1; MCC9-12.A.REI.3; MCC9-12.A.REI.5; MCC9-12.A.REI.6; MCC9-12.A.REI.12)

2. Solving a System of Equations
by Substitution
Step 1 Isolate one variable.
Step 2 Substitute that expression into the second equation.
Step 3
Solve for the variable.
Step 4
Substitute the value into one of the original equations.
Step 5
Solve for the remaining variable. 7
4x - y = 0
x - 2y = -7
+2y +2y
x = 2y - 7
4(2y – 7) - y = 0
8y – 28 - y = 0
7y – 28 = 0
7y – 28 = 0
7y = 28 7
y = 4
x – 2(4) = -7
x – 8 = -7
x – 8 = -7
x = 1
(1, 4)
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia Adapted from various sources (MCC9-12.A.REI.1; MCC9-12.A.REI.3; MCC9-12.A.REI.5; MCC9-12.A.REI.6; MCC9-12.A.REI.12)