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You did these with your group. Now do them on your own — the model above is yours to copy.

1. 1

   Same stepsFinish what the group started. Use the model above, step for step.

   Try it together — then prove it: The committee buys one $4.25 item for each student, plus $23.50 shipping one time. Write an expression. Find the cost for 30 students. Let s be the number of students. Write the expression. (4.25s + 23.50) Substitute s = 30 and evaluate. (4.25 × 30 + 23.50 = 127.50 + 23.50 = 151) Why is 23.50 added once, but 4.25 is multiplied by s? (Shipping is paid one time. The $4.25 is paid for each student, so that part grows with s.)

   Show your work
2. 2

   Warm restartIn the expression 4 + 6 ÷ 2, which operation do you do first?

   1. AAdd 4 and 6
   2. BDivide 6 by 2
   3. CEither order gives the same answer
   4. DSubtract

   How do you know?
3. 3

   Warm restartA square room has sides of 7 feet. Which expression gives its area, and what is the value?

   1. A2⁷ = 128
   2. B7² = 49
   3. C7 × 2 = 14
   4. D7 + 7 = 14

   How do you know?
4. 4

   Warm restartEvaluate: 5 + 3 × 2²

   1. A17
   2. B26
   3. C32
   4. D64

   How do you know?

You answered these out loud. Now write them.

Answer, then say how you know — the reason is the part that counts.

1. 5

   Think it throughWhich expression models the total cost for h hours?

   1. A8 + 25h
   2. B25 + 8h
   3. C25h + 8h
   4. D33h

   Why is that the answer?
2. 6

   Think it throughWhat is the total cost for 6 hours?

   1. A$33
   2. B$48
   3. C$73
   4. D$198

   How do you know? Give a second reason as well.
3. 7

   Think it throughIn 25 + 8h, what is the coefficient?

   1. A25
   2. B8
   3. Ch
   4. D25h

   Explain your thinking. What would have to change for a different choice to be right?
4. 8

   Back to the modelWhat key words helped you decide which operation to use? How can the same phrase be written differently?

Use the words

Fill each blank with a word from the bank.

• A letter that stands for an unknown number is a ___.
• A math phrase with variables, numbers, and operations but no equal sign is an ___.
• The number multiplied by a variable, like the 7 in 7n, is the ___.
• A term that is just a number and never changes, like the 5 in 3x + 5, is a ___.

Explain the thinking

1. 9

   Find the mistakeAnother student made this exact mistake in this lesson. Explain why it is wrong, then write what they should have done.

   The mistake: A common mistake in Write Algebraic Expressions is treating 'each' or 'per' as if it means add instead of multiply, and attaching the variable to the wrong number.
2. 10

   Say moreHow do you turn words into an expression? Why does '12 less than a number g' become g − 12 and not 12 − g?
3. 11

   Write your ownWrite your own problem about this situation, then solve it and show the answer. The situation: Evelyn is booking a recording session at the music studio for her band. The studio charges the same price for every hour of recording time, plus a one-time setup fee of $23.50. The band does not yet know how many hours they will record.

   Show your work

Last check

These two come from Lesson 6.4. If they are shaky, that is the lesson to revisit — not this one.

1. 12

   Show what you knowExplain your thinking — A club orders one $4.25 shirt for each student plus a one-time $23.50 shipping fee. Write the expression for s students, then find the cost for 30 students.

   1. A4.25s + 23.50; for s = 30 the cost is $151.00
   2. B4.25s + 23.50; for s = 30 the cost is $832.50
   3. C4.25 + 23.50s; for s = 30 the cost is $709.25
   4. D27.75s; for s = 30 the cost is $832.50

   Explain your choice.
2. 13

   From Lesson 6.4Explain your thinking — Evaluate 2 × 15 + 8 × 2³.

   1. A94
   2. B124
   3. C150
   4. D736

   How do you know?
3. 14

   From Lesson 6.4What does the 1.75 represent?

   1. AThe base fee
   2. BThe total cost
   3. CThe number of miles
   4. DThe cost per mile, multiplied by the number of miles

   How do you know?

Be honest — this tells your teacher what to do next