Grade 5 Pre-Algebra worksheet for evaluating algebraic expressions with one variable.

Let's solve the algebraic expressions step by step based on the worksheet you provided.

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Part A: Evaluate each expression when $ x = 9 $

We substitute $ x = 9 $ into each expression:

1) $ x + 12 = 9 + 12 = \boxed{21} $

2) $ 8 + x = 8 + 9 = \boxed{17} $

3) $ 20 + x = 20 + 9 = \boxed{29} $

4) $ 4 + x = 4 + 9 = \boxed{13} $

5) $ x + 14 - 15 = 9 + 14 - 15 = 23 - 15 = \boxed{8} $

6) $ x - 3 = 9 - 3 = \boxed{6} $

7) $ 1 + x = 1 + 9 = \boxed{10} $

8) $ x - 1 = 9 - 1 = \boxed{8} $

9) $ x + 11 = 9 + 11 = \boxed{20} $

10) $ x + 6 = 9 + 6 = \boxed{15} $

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Part B: Evaluate each expression when $ y = 5 $

Now substitute $ y = 5 $ into each expression:

11) $ y + 7 = 5 + 7 = \boxed{12} $

12) $ y + 18 = 5 + 18 = \boxed{23} $

13) $ y - 5 = 5 - 5 = \boxed{0} $

14) $ 12 + y = 12 + 5 = \boxed{17} $

15) $ y + 14 - 13 = 5 + 14 - 13 = 19 - 13 = \boxed{6} $

16) $ 11 - y = 11 - 5 = \boxed{6} $

17) $ y - 2 = 5 - 2 = \boxed{3} $

18) $ 9 + y = 9 + 5 = \boxed{14} $

19) $ y + 7 = 5 + 7 = \boxed{12} $

20) $ y + 15 - 5 = 5 + 15 - 5 = 20 - 5 = \boxed{15} $

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✔ Final Answers:

Part A (x = 9):
1) 21
2) 17
3) 29
4) 13
5) 8
6) 6
7) 10
8) 8
9) 20
10) 15

Part B (y = 5):
11) 12
12) 23
13) 0
14) 17
15) 6
16) 6
17) 3
18) 14
19) 12
20) 15

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🔍 Explanation:

- Substitution: We replaced every instance of the variable $ x $ or $ y $ with its given value.
- Order of Operations: In expressions like $ x + 14 - 15 $, we perform operations from left to right since they are all addition/subtraction.
- Simplification: After substitution, we simplified each expression to get a single number.

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