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Answer Key
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4
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Date
Class
Practice A
1-1 Variables and Expressions Evaluate each expression. 1. 3 y for y 7
2. 6x for x 3
3. a 11 for a 18
4. r 8 for r 21
5. 3b for b 12
6. 12y for y ᎏ2ᎏ
7. f 32 for f 29
8. 38t for t 1.4
1
9. 7.3 k for k 14
10. s 21.4 for s 22.3
11. x y for x 7 and y 11
12. ab for a 1.5 and b 5
13. j h for h 9 and j 22
14. 2a b for a 6 and b 7
15. 8c 6d for c 5 and d 3
16. 7(x y) for x 18 and y 14
The cost of greeting cards at Discount Cards Plus is $0.60. How much does it cost for each number of greeting cards? 17. 2 cards
18. 5 cards
19. 10 cards
20. 35 cards
21. Mrs. Williams is driving on the interstate at a rate of 58 mi/h. a. Write an expression for the distance she will drive in x hours at this rate. b. How far will she drive in 4.5 hours at this rate?
Copyright © by Holt, Rinehart and Winston. All rights reserved.
9
Holt Middle School Math
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CHAPTER
1
|| Print ||
Are You Ready? Recording Sheet
CHAPTER
1
Algebra Toolbox
subtraction
1.
opposite operation
is the
Algebra Toolbox (continued)
Simplify each expression.
Choose the best term from the list to complete each sentence. addition Associative Property Commutative Property opposite operation multiplication subtraction
Are You Ready? Recording Sheet
17. 2 3 • 4
division
18. 50 2 • 5
14
40
19. 6 • 3 • 3 3
of addition.
20. (5 2)(5 2)
51 2. The expressions 3 • 4 and 4 • 3 are equal by the
Commutative Property
.
Associative Property
.
3. The expressions 1 (2 3) and (1 2) 3 are equal by the
addition
5.
2
are opposite operations.
multiplication
and
22. 16 4 2 • 3
10
23. (8 3)(8 3)
division
4. Multiplication and
21
21. 5 6 2
24. 12 3 2 5
55
7
Determine whether the given expressions are equal.
are commutative.
no
25. (4 7) • 2 and 4 • (7 • 2)
Simplify each expression. 6. 8 116 43
7. 2431 187
167
26. (2 • 4) 2 and 2 • (4 2)
2244
no no
27. 2 • (3 3) • 2 and 2 • 3 3
9. 6447 21
8. 204 • 38
yes
28. 5(50 44) and 5 • (50 44)
7752
307
29. 5 (4 • 2) and (5 4) • 2
no
Order each set of numbers from least to greatest.
yes
10. 1050; 11,500; 105; 150
105; 150; 1050; 11,500
30. 2 • 3 2 • 4 and 2 • (3 4)
11. 503; 53; 5300; 5030
53; 503; 5030; 5300
31. (16 4) 4 and 16 (4 4)
40,040; 40,400; 44,040; 44,400
12. 44,400; 40,040; 40,400; 44,040
32. 5 (2 • 3) and (5 2) • 3
no
no
Rewrite each expression using the inverse operation. 13. 72 18 90
14. 12 • 9 108
90 18 72
108 9 12
15. 100 34 66
16. 56 8 7
66 34 100
7 • 8 56 3
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Middle School Math
Exploration Recording Sheet 1-1 Variables and Expressions
Practice A 1-1 Variables and Expressions
Catherine’s dance team is planning a spring trip to the coast. Catherine is saving money in a bank account to pay for the trip. Her parents started her account with $100. She sells Christmas plants and adds $2.50 to her account for each plant she sells.
Evaluate each expression. 1. 3 y for y 7
2. 6x for x 3
10
How much will be in her account if she sells 50 plants?
18
3. a 11 for a 18
4. r 8 for r 21
7
Price number of plants
13 1
6. 12y for y ᎏ2ᎏ
5. 3b for b 12
100 2.5n
36
6
7. f 32 for f 29
Evaluate the expression 100 2.5n by substituting 50 for n.
8. 38t for t 1.4
61
100 2.5(50)
53.2
9. 7.3 k for k 14
100 125 225
10. s 21.4 for s 22.3
21.3
There will be $225.00 in Catherine’s account if she sells 50 plants.
1. n 10
100 2.5(10)
2. n 25
100 2.5( 100 2.5(
25 75
7.5
13. j h for h 9 and j 22
100 62.50 $162.50
14. 2a b for a 6 and b 7
13
19
15. 8c 6d for c 5 and d 3
100 187.50 $287.50
)
12. ab for a 1.5 and b 5
18
100 25 $125 )
0.9
11. x y for x 7 and y 11
Evaluate the expression 100 2.5n for each value of n.
3. n 75
Holt Middle School Math
LESSON
LESSON
Initial amount
4
Copyright © by Holt, Rinehart and Winston. All rights reserved.
16. 7(x y) for x 18 and y 14
22
Think and Discuss
28
The cost of greeting cards at Discount Cards Plus is $0.60. How much does it cost for each number of greeting cards?
4. Explain why n is called the variable in the expression 100 2.5n.
17. 2 cards
Possible answer: It is the variable since it changes depending on
$1.20
18. 5 cards
19. 10 cards
$3.00
20. 35 cards
$6.00
$21.00
the number of plants sold. 21. Mrs. Williams is driving on the interstate at a rate of 58 mi/h.
5. Describe how to evaluate an expression.
a. Write an expression for the distance she will drive in x hours
Possible answer: Substitute the given value for the variable and
at this rate.
then multiply.
58x
b. How far will she drive in 4.5 hours at this rate?
Copyright © by Holt, Rinehart and Winston. All rights reserved.
8
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Middle School Math
Copyright © by Holt, Rinehart and Winston. All rights reserved.
106
9
261 miles
Holt Middle School Math
Holt Middle School Math