Warm Up

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Warm Up
Problem of the Day
Lesson Presentation
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Warm Up Solve. 1. x 15 9 2. x 21 34 3.
17 x 11 4. 22 x 34
x 24
x 13
x 28
x 56
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Problem of the Day If a newborn baby weighs two
pounds plus three-fourths its own weight, how
much does it weigh?
8 pounds
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Learn to solve equations by adding and
subtracting fractions.
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Additional Example 1A Solving Equations by
Adding and Subtracting Solve each equation. Write
the solution in simplest form.
x 5 14
x 5 14
5 5
______ ______
x 13 5
x 8
Subtract.
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Additional Example 1B Solving Equations by
Adding and Subtracting Solve each equation. Write
the solution in simplest form.
3 x 4
3 x 4
4 4
______ ________
3 4 x
Find a common denominator.
7 x
Add.
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Additional Example 1C Solving Equations by
Adding and Subtracting Solve each equation. Write
the solution in simplest form.
6 m
6 m
Subtract from both sides to undo the
addition.

______ ______
6 m
Find a common denominator.
5 m
Regroup 6 as 5 .
5 m
Subtract.
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Additional Example 1D Solving Equations by
Adding and Subtracting Solve each equation. Write
the solution in simplest form.
w 3
w 3

Add to both sides to undo subtraction.
_____ _____
Find a common denominator.
w 3
w 3
Add.
3 3 1
w 3
w 4
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Check It Out Example 1A Solve each equation.
Write the solution in simplest form.
x 3 12
x 3 12
3 3
______ ______
x 11 3
x 8
Subtract.
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Check It Out Example 1B Solve each equation.
Write the solution in simplest form.
2 x 3
2 x 3
3 3
______ ______
2 3 x
Find a common denominator.
5 x
Add.
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Check It Out Example 1C Solve each equation.
Write the solution in simplest form.
5 m
5 m
Subtract from both sides to undo the
addition.

______ ______
5 m
Find a common denominator.
4 m
Regroup 5 as 4 .
4 m
Subtract.
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Check It Out Example 1D Solve each equation.
Write the solution in simplest form.
w 5
w 5

Add to both sides to undo subtraction.
_____ _____
w 5
Find a common denominator.
w 5
Add.
5 5 1
w 5
w 6
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Additional Example 2 Application
Lindas dog weighs 85 pounds. If Lindas dog
weighs 17 pounds less than Ians dog, how
much does Ians dog weigh?
Let d represent the weight of Ians dog.
d 17 85
17 17
Add 17 to both sides to undo the subtraction.

________ ________
d 102
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Additional Example 2 Continued Check
d 17 85
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102 17 85
Substitute 102 for d.
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Find a common denominator.
102 17 85
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102 is the solution.
85 85
Ians dog weighs 102 pounds.
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Check it Out Example 2
Jimmys cat weighs 13 pounds. If Jimmys cat
weighs 4 pounds less than Vickis cat, how
much does Vickis cat weigh?
Let c represent the weight of Vickis cat.
c 4 13
4 4
Add 4 to both sides to undo the subtraction.

_______ ________
c 17
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Check it Out Example 2 Check
c 4 13
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17 4 13
Substitute 17 for c.
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Find a common denominator.
17 4 13
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17 is the solution.
13 13
Vickis cat weighs 17 pounds.
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Lesson Quiz
Solve each equation. Write the solution in
simplest form. 1. x 3 2 2. x 6
11 3. 1 x 2 4. 5 x 5. Marco
needs to work 40 hours per week. He has worked 31
hours so far this week. How many hours does he
need to work on Friday to meet his 40-hour
requirement?
4
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5
8 hours