UA · Unit 5 review

1. 1.

   Which expression is equivalent to 5(x + 5) + 3?

   Answer. 5x + 28

   Distribute: 5x + 25. Then add 3: 5x + 28.

2. 2.

   Is x = 6 a solution of 6x = 30?

   Answer. no

   6(6) = 36, which does not equal 30.

3. 3.

   Solve 5x + 5 = 45.

   Answer. x = 8

   Subtract 5: 5x = 40. Divide by 5: x = 8.

4. 4.

   The rule is y = 6x + 8. What is y when x = 7?

   Answer. 50

   y = 6(7) + 8 = 42 + 8 = 50.

5. 5.

   Which expression is equivalent to 2(x + 3) + 4? Then Sam needs 4 of that amount. What is the total they need?

   Answer. 8x + 10

   Distribute: 2x + 6. Then add 4: 2x + 10. Then multiply by 4: 8x + 10.

6. 6.

   Is x = 5 a solution of 3x = 6? Write a complete answer — Nora will compare with a partner.

   Answer. no

   3(5) = 15, which does not equal 6.

7. 7.

   Priya’s tickets cost $6 each and the total is $12. How many tickets did Priya buy? Then Priya gives 1 away. How many are left?

   Answer. 1

   6x = 12 → x = 2 tickets. After giving 1 away: 1.

8. 8.

   The rule is y = 6x + 6. What is y when x = 3? Then Ava needs 2 of that amount. What is the total they need?

   Answer. 48

   y = 6(3) + 6 = 18 + 6 = 24. Then multiply by 2: 48.

9. 9.

   Which expression is equivalent to 6(x + 2) + 1? Then Luis needs 3 of that amount. What is the total they need?

   Answer. 18x + 13

   Distribute: 6x + 12. Then add 1: 6x + 13. Then multiply by 3: 18x + 13.

10. 10.

    Is x = 8 a solution of 3x = 15? Write a complete answer — Grace will compare with a partner.

    Answer. no

    3(8) = 24, which does not equal 15.

11. 11.

    Think

    Malik solved x + 4 = 13 by adding 4 to 13 and got 17. What is x?

    Answer. x = 9

    Undo addition with subtraction: x = 13 − 4 = 9.

12. 12.

    Think

    Nora tried this problem:
    The rule is y = 3x + 3. What is y when x = 2?
    Nora wrote 18. That is not correct. What is the right answer?

    Answer. 9

    Nora’s answer 18 is off. y = 3(2) + 3 = 6 + 3 = 9.

Original extra practice. Keys are computed from the items, not guessed.