lesson one

Copyright © by Holt, Rinehart and Winston. 9 Holt Middle School MathAll rights reserved.

Name Date Class

Practice AVariables and Expressions 1-1

LESSON

Evaluate each expression.

1. 3 � y for y � 7

3. a � 11 for a � 18

5. 3b for b � 12

7. f � 32 for f � 29

9. 7.3 � k for k � 14

11. x � y for x � 7 and y � 11

13. j � h for h � 9 and j � 22

15. 8c � 6d for c � 5 and d � 3

2. 6x for x � 3

4. r � 8 for r � 21

6. 12y for y � �12

�

8. 38t for t � 1.4

10. s � 21.4 for s � 22.3

12. ab for a � 1.5 and b � 5

14. 2a � b for a � 6 and b � 7

16. 7(x � y) for x � 18 and y � 14

The cost of greeting cards at Discount Cards Plus is $0.60. Howmuch 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?



Choose the best term from the list to complete each sentence.

addition Associative Property Commutative Property divisionopposite operation multiplication subtraction

1. is the of addition.

2. The expressions 3 • 4 and 4 • 3 are equal by the .

3. The expressions 1 � (2 � 3) and (1 � 2) � 3are equal by the .

4. Multiplication and are opposite operations.

5. and are commutative.

Simplify each expression.

6. 8 � 116 � 43 7. 2431 � 187

8. 204 • 38 9. 6447 � 21

Order each set of numbers from least to greatest.

10. 1050; 11,500; 105; 150

11. 503; 53; 5300; 5030

12. 44,400; 40,040; 40,400; 44,040

Rewrite each expression using the inverse operation.

13. 72 � 18 � 90 14. 12 • 9 � 108

15. 100 � 34 � 66 16. 56 � 8 � 7

7 • 8 � 5666 � 34 � 100

108 � 9 � 1290 � 18 � 72

40,040; 40,400; 44,040; 44,400

53; 503; 5030; 5300

105; 150; 1050; 11,500

3077752

2244167

multiplicationaddition

division

Associative Property

Commutative Property

opposite operationsubtraction

Are You Ready? Recording SheetAlgebra Toolbox1

CHAPTER

Simplify each expression.

17. 2 � 3 • 4 18. 50 � 2 • 5

19. 6 • 3 • 3 � 3 20. (5 � 2)(5 � 2)

21. 5 � 6 � 2 22. 16 � 4 � 2 • 3

23. (8 � 3)(8 � 3) 24. 12 � 3 � 2 � 5

Determine whether the given expressions are equal.

25. (4 � 7) • 2 and 4 • (7 • 2)

26. (2 • 4) � 2 and 2 • (4 � 2)

27. 2 • (3 � 3) • 2 and 2 • 3 � 3

28. 5(50 � 44) and 5 • (50 � 44)

29. 5 � (4 • 2) and (5 � 4) • 2

30. 2 • 3 � 2 • 4 and 2 • (3 � 4)

31. (16 � 4) � 4 and 16 � (4 � 4)

32. 5 � (2 • 3) and (5 � 2) • 3 no

no

yes

no

yes

no

no

no

755

102

2151

4014


Are You Ready? Recording SheetAlgebra Toolbox (continued)1

CHAPTER

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 Christmasplants and adds $2.50 to her account for each plant she sells.

How much will be in her account if she sells 50 plants?

Evaluate the expression 100 � 2.5n by substituting 50 for n.

100 � 2.5(50)

100 � 125

225

There will be $225.00 in Catherine’s account if she sells 50 plants.

Evaluate the expression 100 � 2.5n for each value of n.

1. n � 10 100 � 2.5(10) �

2. n � 25 100 � 2.5( ) �

3. n � 75 100 � 2.5( ) �

Think and Discuss

4. Explain why n is called the variable in the expression 100 � 2.5n.

Possible answer: It is the variable since it changes depending on

the number of plants sold.5. Describe how to evaluate an expression.

Possible answer: Substitute the given value for the variable and

then multiply.

100 � 187.50 � $287.5075

100 � 62.50 � $162.5025

100 � 25 � $125


Exploration Recording SheetVariables and Expressions1-1

LESSON

100 � 2.5n

Initial amount Price � number of plants


Practice AVariables and Expressions1-1

LESSON

Evaluate each expression.

1. 3 � y for y � 7

103. a � 11 for a � 18

75. 3b for b � 12

367. f � 32 for f � 29

619. 7.3 � k for k � 14

21.311. x � y for x � 7 and y � 11

1813. j � h for h � 9 and j � 22

1315. 8c � 6d for c � 5 and d � 3

22

2. 6x for x � 3

184. r � 8 for r � 21

136. 12y for y � �

12

�

68. 38t for t � 1.4

53.210. s � 21.4 for s � 22.3

0.912. ab for a � 1.5 and b � 5

7.514. 2a � b for a � 6 and b � 7

1916. 7(x � y) for x � 18 and y � 14

28

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? 261 miles

58x

$21.00$6.00$3.00$1.20

lesson one

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