Warm Up

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Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes
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Warm Up Determine whether each value is a
solution. 1. 86 x 102 for x 16 2. 18 x
26 for x 4 3. x 46 214 for x 168 4. 9
x 35 for x 26
yes
no
yes
yes
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42____ 23____
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Problem of the Day Renee went to the closet to
get her kite string. After Renee used 40 m of
string for her kite and gave 5 m to her sister
for her wagon, she had 8 m of string left. How
much string did she have to start with?
53 m
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Learn to solve whole-number addition equations.
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Vocabulary
inverse operations
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The equation h 14 82 can be represented as a
balanced scale.
To find the value of h, you need h by itself on
one side of the scale.
To get h by itself, first take away 14 from the
left side of the scale. Now the scale is
unbalanced.
To rebalance the scale, take away 14 from the
other side.
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Taking away 14 from both sides of the scale is
the same as subtracting 14 from both sides of the
equation.
h 14 82
14
14
h 68
Inverse operations undo each other. Addition and
subtraction are inverse operations. If an
equation contains addition, solve it by
subtracting from both sides to undo the
addition.
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Additional Example 1A Solving Addition Equations
Solve the equation. Check your answer.
x 87 152
x 87 152
87 is added to x.
87
87
Subtract 87 from both sides to undo the addition.
x 65
Check x 87 152
Substitute 65 for x in the equation.
?
65 is the solution.
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Additional Example 1B Solving Addition Equations
Solve the equation. Check your answer.
72 18 y
72 18 y
18 is added to y.
18
18___
Subtract 18 from both sides to undo the addition.
54 y
Check 72 18 y
Substitute 54 for y in the equation.
?
54 is the solution.
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Check It Out Example 1A
Solve the equation. Check your answer.
u 43 78
u 43 78
43 is added to u.
___ 43
43
Subtract 43 from both sides to undo the addition.
u 35
Check u 43 78
Substitute 35 for u in the equation.
?
35 is the solution.
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Check It Out Example 1B
Solve the equation. Check your answer.
68 24 g
68 24 g
24 is added to g.
24
24___
Subtract 24 from both sides to undo the addition.
44 g
Check 68 24 g
Substitute 44 for g in the equation.
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44 is the solution.
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Additional Example 2 Social Studies Application
Johnstown, Cooperstown, and Springfield are
located in that order in a straight line along a
highway. It is 12 miles from Johnstown to
Cooperstown and 95 miles from Johnstown to
Springfield. Find the distance d between
Cooperstown and Springfield.
distance between Johnstown and Springfield
distance between Johnstown and Cooperstown
distance between Cooperstown and Springfield


95 12
d
95 12 d
12 is added to d.
Subtract 12 from both sides to undo the addition.
12
12___
83 d
It is 83 miles from Cooperstown to Springfield.
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Check It Out Example 2
Patterson, Jacobsville, and East Valley are
located in that order in a straight line along a
highway. It is 17 miles from Patterson to
Jacobsville and 35 miles from Patterson to East
Valley. Find the distance d between Jacobsville
and East Valley.
distance between Patterson and East Valley
distance between Patterson and Jacobsville
distance between Jacobsville and East Valley


35 17
d
35 17 d
17 is added to d.
17___
Subtract 17 from both sides to undo the addition.
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18 d
It is 18 miles from Jacobsville to East Valley.
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Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems
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Lesson Quiz
Solve each equation. 1. x 15 72 2. 81 x
24 3. x 22 67 4. 93 x 14
x 57
x 57
x 45
x 79
5. Kaitlin is 2 inches taller than Reba. Reba is
54 inches tall. How tall is Kaitlin?
56 inches
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Lesson Quiz for Student Response Systems
1. Solve the solution of the x 26 75. A. x
39 B. x 49 C. x 59 D. x 101
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Lesson Quiz for Student Response Systems
2. Solve the solution of the 71 y 47. A. y
24 B. y 28 C. y 108 D. y 118
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Lesson Quiz for Student Response Systems
3. Solve the solution of the z 37 65. A. z
102 B. z 92 C. z 38 D. z 28
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Lesson Quiz for Student Response Systems
4. Solve the solution of the 76 x 39. A. x
27 B. x 37 C. x 95 D. x 115
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Lesson Quiz for Student Response Systems
5. Steven has 9 more music CDs than Carol. Steven
has 25 music CDs. How many music CDs does Carol
have? A. 7 music CDs B. 9 music CDs C. 16
music CDs D. 25 music CDs