1. Solving Systems of Equations using Substitution

2. Solving a system by graphing isn’t always the most effective method.
Solve by Graphing
Review
Solving a system by graphing isn’t always the most effective method.

3. Steps for Solving Systems using Substitution
Solve one of the equations for either x or y.
Look for the variable that seems easiest to solve for
Substitute that quantity into the other equation.
Substitute the first answer into either of the original equations to find the second answer.
Check the answer in both equations.

4. Solve using substitution.
Solution is (2, 4)

5. Solve using substitution.

6. Solve using substitution.

7. Solve using substitution.

8. Solve using substitution.

9. Solve using substitution.

10. Chatty Phone charges a flat monthly fee of $20
plus 8¢ a minute. Telco charges $14 plus
10¢ a minute. When do they charge the same?
Let m = minutes
Let t = total cost
Chatty
Telco
At 300 min.
they charge
the same.