Grade 5 Pre-Algebra worksheet focusing on evaluating algebraic expressions with one variable, including addition, subtraction, and simple equations.

Problem Description:

The task involves evaluating algebraic expressions for two different variables:
1. Part A: Evaluate each expression when \( x = 9 \).
2. Part B: Evaluate each expression when \( y = 5 \).

We will solve each part step by step.

---

Part A: Evaluate each expression when \( x = 9 \)

#### 1) \( x + 12 \)
Substitute \( x = 9 \):
\[
x + 12 = 9 + 12 = 21
\]

#### 2) \( 8 \times x \)
Substitute \( x = 9 \):
\[
8 \times x = 8 \times 9 = 72
\]

#### 3) \( 20 + x \)
Substitute \( x = 9 \):
\[
20 + x = 20 + 9 = 29
\]

#### 4) \( 4 \times x \)
Substitute \( x = 9 \):
\[
4 \times x = 4 \times 9 = 36
\]

#### 5) \( x + 14 - 15 \)
Substitute \( x = 9 \):
\[
x + 14 - 15 = 9 + 14 - 15 = 23 - 15 = 8
\]

#### 6) \( x - 3 \)
Substitute \( x = 9 \):
\[
x - 3 = 9 - 3 = 6
\]

#### 7) \( 1 + x \)
Substitute \( x = 9 \):
\[
1 + x = 1 + 9 = 10
\]

#### 8) \( x - 1 \)
Substitute \( x = 9 \):
\[
x - 1 = 9 - 1 = 8
\]

#### 9) \( x + 11 \)
Substitute \( x = 9 \):
\[
x + 11 = 9 + 11 = 20
\]

#### 10) \( x + 6 \)
Substitute \( x = 9 \):
\[
x + 6 = 9 + 6 = 15
\]

---

Part B: Evaluate each expression when \( y = 5 \)

#### 11) \( y + 17 \)
Substitute \( y = 5 \):
\[
y + 17 = 5 + 17 = 22
\]

#### 12) \( y + 18 \)
Substitute \( y = 5 \):
\[
y + 18 = 5 + 18 = 23
\]

#### 13) \( y - 5 \)
Substitute \( y = 5 \):
\[
y - 5 = 5 - 5 = 0
\]

#### 14) \( 12 + y \)
Substitute \( y = 5 \):
\[
12 + y = 12 + 5 = 17
\]

#### 15) \( y + 14 - 13 \)
Substitute \( y = 5 \):
\[
y + 14 - 13 = 5 + 14 - 13 = 19 - 13 = 6
\]

#### 16) \( 11 - y \)
Substitute \( y = 5 \):
\[
11 - y = 11 - 5 = 6
\]

#### 17) \( y - 2 \)
Substitute \( y = 5 \):
\[
y - 2 = 5 - 2 = 3
\]

#### 18) \( 9 + y \)
Substitute \( y = 5 \):
\[
9 + y = 9 + 5 = 14
\]

#### 19) \( y + 7 \)
Substitute \( y = 5 \):
\[
y + 7 = 5 + 7 = 12
\]

#### 20) \( y + 15 - 5 \)
Substitute \( y = 5 \):
\[
y + 15 - 5 = 5 + 15 - 5 = 20 - 5 = 15
\]

---

Final Answers:

\[
\boxed{
\begin{array}{ll}
\text{Part A:} & 1) 21, \, 2) 72, \, 3) 29, \, 4) 36, \, 5) 8, \, 6) 6, \, 7) 10, \, 8) 8, \, 9) 20, \, 10) 15 \\
\text{Part B:} & 11) 22, \, 12) 23, \, 13) 0, \, 14) 17, \, 15) 6, \, 16) 6, \, 17) 3, \, 18) 14, \, 19) 12, \, 20) 15
\end{array}
}
\]