1. Objective The student will be able to:
solve literal equations (formulas) for a specified variable.
SOL: A.1
Designed by Skip Tyler, Varina High School

2. 1) Solve 2x - 4y = 7 for x To get x by itself, what is the first step?
Add 2x
Subtract 2x
Add 4y
Subtract 4y
Answer Now

3. 1) Solve 2x - 4y = 7 for x Use a DO-UNDO chart to help determine the steps
Ask yourself,
What is the first thing we are doing to x?
What is the second thing?
DO UNDO
· 2
-4y
Follow the steps in the ‘undo’ column to isolate the variable.
+4y
÷ 2
Complete the undo column by writing the opposite operations in opposite order.

4. 1) Solve 2x - 4y = 7 for x + 4y + 4y 2x = 7 + 4y 2 2 Draw “the river”
D U
1) Solve 2x - 4y = 7 for x
· 2
-4y
+4y
÷ 2
+ 4y + 4y
2x = y
Draw “the river”
Add 4y to both sides
Simplify
Divide both sides by 2
Does it simplify?
This fraction cannot be simplified because both terms in the numerator are not divisible by 2.

5. 2) Solve 2x - 4y = 7 for y To get y by itself, what is the first step?
Add 2x
Subtract 2x
Add 4y
Subtract 4y
Answer Now

6. 2) Solve 2x - 4y = 7 for y - 2x - 2x -4y = 7 - 2x -4 -4
D U
2) Solve 2x - 4y = 7 for y
· -4
+2x
-2x
÷ -4
- 2x x
-4y = 7 - 2x
Draw “the river”
Subtract 2x from both sides
Simplify
Divide both sides by -4
Does it simplify?
Nope!

7. 3) Solve for y. What is the first step?
Multiply by 3
Divide by 3
Add a
Subtract a
Answer Now

8. 3) Solve for y: y + a = 3c -a -a y = 3c - a Draw “the river”
D U
3) Solve for y:
+ a
÷ 3
· 3
- a
Draw “the river”
Clear the fraction – multiply both sides by 3
Simplify
Subtract a from both sides
y + a = 3c
-a -a
y = 3c - a

9. 4) Solve for y: 4x – 2y = 12 -4x + 12 4x - 12 -2x + 6 2x - 6
Answer Now

10. 4) Solve for y: 4x – 2y = 12 - 4x - 4x -2y = 12 – 4x -2 -2 y = -6 + 2x
D U
4) Solve for y: 4x – 2y = 12
· -2
+ 4x
- 4x
÷ -2
- 4x x
-2y = 12 – 4x
y = x
or y = 2x - 6
Draw “the river”
Subtract 4x from both sides
Simplify
Divide both sides by -2
Does it simplify?
Yes!

11. 5) The formula for the volume of a rectangular prism is V = LWH
5) The formula for the volume of a rectangular prism is V = LWH. Which equation solves the formula for L?
L = V - WH
Answer Now

12. 6) The formula for the volume of a pyramid is V =
6) The formula for the volume of a pyramid is V = Which equation solves the formula for h?
h = 3Vb
Answer Now