1. Solving a system of equations by SUBSTITUTION
Step 1: Solve an equation for one variable.
Pick the easier equation. The goal
is to get y= ; x= ; a= ; etc.
Step 2: Substitute
Put the equation solved in Step 1
into the other equation.
Step 3: Solve the equation.
Get the variable by itself.
Step 4: Plug back in to find the other variable.
Substitute the value of the variable
into the equation.
Step 5: Check your solution.
Substitute your ordered pair into
BOTH equations.

2. 1) Solve the system using substitution
x + y = 5
y = 3 + x
Step 1: Solve an equation for one variable.
The second equation is
already solved for y!
Step 2: Substitute
x + y = 5 x + (3 + x) = 5
2x + 3 = 5
2x = 2
x = 1
Step 3: Solve the equation.

3. 1) Solve the system using substitution
x + y = 5
y = 3 + x
x + y = 5
(1) + y = 5
y = 4
Step 4: Plug back in to find the other variable.
(1, 4)
(1) + (4) = 5
(4) = 3 + (1)
Step 5: Check your solution.
The solution is (1, 4). What do you think the answer would be if you graphed the two equations?

4. Solve the system using substitution
3x – y = 4
x = 4y - 17

5. Solving a system of equations by SUBSTITUTION
Pick the easier equation. The goal
is to get y= ; x= ; a
Step 1:
Pick the easier equation. The goal
is to get y= ; x= ; a= ; etc. .
Put the equation solved in Step 1
into the other equation
Using the equation solved in Step 1 replace the variable in the other equation. Therefore you have one equation with one variable.
Step 2:
he variable by itself.
ck the easier equation. The goal
is to get y= ; x= ; a= ; etc
Step 3:
Get the variable by itself. .
Substitute the value of the variable into the equation. Write your answer as an ordered pair (x, y).
Step 4:

6. REAL WORLD APP
You buy a total of 50 burgers and hotdogs for $90. You pay $2 per burger and $1.50 per hotdog.
Write a system of equations to find the number of x burgers and y hotdogs.

7. Solve the system by substitution
_______burgers and ______hotdogs

8. Try this:
You sell lemonade for $2 per cup and orange juice for $3 per cup. You sell a total of 100 cups for $240.
Write a system of equations to find the number of x cups of lemonade and y cups of orange juice.

9. Solve the system by substitution
_______cups lemonade & ______cups orange juice