Keeping the Meaning in Mathematics: The Craft of Word Problems

CONTENTS OF CURRICULUM UNIT 07.06.07

  1. Unit Guide
  1. Rationale
  2. Strategies
  3. Ice -Breaker - I
  4. Lesson One - Notation Development (whole class discussion)
  5. Lesson Two - Simplifying Expressions
  6. Lesson Three - Translations of Verbal Descriptions (addition/subtraction)
  7. Lesson Four - Translations of Verbal Descriptions (multiplication/division)
  8. Lesson Five - Distributive Property
  9. Lesson 6 - Combination - These problems combines all the components of the unit for reinforcement.
  10. Lesson Seven - Application and Reinforcement
  11. Appendix 1 - ALGEBRAIC OPERATIONS
  12. BIBLIOGRAPHY FOR TEACHERS
  13. STUDENTS RESOUCRES
  14. Classroom Material
  15. Implementing District Standards

Linear Expressions and Evaluations

Angel Johnson

Published September 2007

Tools for this Unit:

Lesson Five - Distributive Property

Sale Prices

Used Games $9.95

Bargain Games $14.95

Regular Games $24.95

New Releases $34.95

Instant Replay Video Games sells new and used games. During a Saturday morning sale, the first "x" customers each bought a bargain game and a new release. Write an expression to calculate the total sales for these customers.

14.95x + 34.95x or (14.95 + 34.95)x = 49.90x

Instant Replay Video Games sells new and used games. During a Saturday morning sale, the first 8 customers each bought a bargain game and a new release. What will be the total sales to these customers? ($399.20)

Problem 1

The Morris family owns two cars. They drove the first car 18,000 miles and the second car 16,000 miles. Write an expression (using the distributive property) to calculate the cost to operate their cars in any year. Let x stand for the cost per mile to operate a car. Suppose that it is the same for the two cars.

18,000x + 16,000x = (18,000 + 16,000)x = 34,000x

Use the table to answer: The Morris family owns two cars. In 1998, they drove the first car 18,000 miles and the second car 16,000 miles. What will it cost the Morris family to operate their cars.

Car costs race ahead Prices (USA Today)

1985 .23

1990 .33

1995 .41

1998 .46

.46(18,000 + 16,000) = 15,640

Write an algebraic expression for each verbal expression. Then simplify, indicating the properties used.

1) twice the sum of s and t decreased by s.

2(s + t) -s

=2s + 2t - s (distributive rule)

=2s -s +2t (commutative rule)

= (2 - 1) s + 2t (distributive rule/combine like terms)

=s + 2t

2) five times the product of two and x increased by 3x

5(2x) + 3x (associative rule for multiplication)

=10x + 3x (combine like terms)

=13x (simplify)

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