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Solve subtraction equations Objective Solve subtraction equations Example 3-3c

Vocabulary None Example 3-3c

Example 1 Solve an Equation by Adding Example 2 Solve a Subtraction Equation Example 3 Use an Equation to Solve a Problem Lesson 3 Contents

Ask “what is being done to the variable?” Write the equation. Ask “what is being done to the variable?” The variable is being subtracted by 5 x – 5 + 5 = 10 + 5 Do the inverse on each side to “undo” the subtraction Bring down x - 5 Add 5 Bring down = 10 Add 5 1/3 Example 3-1a

Use the Identity Property of Addition to add x + 0 x + 0 = 15 Bring down x Combine “like” terms Bring down = Combine “like” terms x – 5 + 5 = 10 + 5 Use the Identity Property of Addition to add x + 0 x + 0 = 15 Answer: x = 15 1/3 Example 3-1a

Answer: w = 12 1/3 Example 3-1c

Ask “what is being done to the variable?” Write the equation. Ask “what is being done to the variable?” The variable is being subtracted by 5 x – 5 + 5 = -1 + 5 Do the inverse on each side to “undo” the subtraction Bring down x - 5 Add 5 Bring down = -1 Add 5 2/3 Example 3-2a

Use the Identity Property of Addition to add x + 0 x + 0 = 4 Bring down x Combine “like” terms Bring down = Combine “like” terms x – 5 + 5 = -1 + 5 Use the Identity Property of Addition to add x + 0 x + 0 = 4 Answer: x = 4 2/3 Example 3-2a

Answer: d = 3 2/3 Example 3-2b

What is the record high temperature in degrees Fahrenheit? The difference between the record high and the record low temperatures in Oregon is 173F. The record low temperature is –54F. What is the record high temperature in degrees Fahrenheit? Difference = high - low Determine process to use 173 = x The word “difference” tells us we need to subtract Replace “difference” with 173 Bring down = Replace “high” with variable 3/3 Example 3-3a

What is the record high temperature in degrees Fahrenheit? The difference between the record high and the record low temperatures in Oregon is 173F. The record low temperature is –54F. What is the record high temperature in degrees Fahrenheit? Difference = high - low Bring down - 173 = x - (- 54) Replace “low” with -54 Remember: With 2 negative signs, put them together to make addition 173 = x + 54 3/3 Example 3-3a

Ask “what is being done to the variable?” Difference = high - low The variable is being added by 54 173 = x - (- 54) 173 = x + 54 Do the inverse on each side to “undo” the addition 173 - 54 = x + 54 - 54 Bring down 173 Subtract 54 Bring down = x + 54 Subtract 54 3/3 Example 3-3a

Use the Identity Property of Addition to add x + 0 173 - 54 = x + 54 Combine “like” terms Difference = high - low Bring down = x 173 = x - (- 54) Combine “like” terms 173 = x + 54 Use the Identity Property of Addition to add x + 0 173 - 54 = x + 54 - 54 Add dimensional analysis 119 = x + 0 What is the record high temperature in degrees Fahrenheit? Answer: 119 = x 0 F 3/3 Example 3-3a

NOTE: Could also be 33 years = x * The difference between the age of Julie’s mother and Julie’s age is 27 years. Julie’s age is 6. What is the age of Julie’s mother? Answer: x = 33 years NOTE: Could also be 33 years = x 3/3 Example 3-3c

Solving Subtraction Equations Assignment Lesson 9:3 Solving Subtraction Equations 12 - 33 All End of Lesson 3