Worksheet: Evaluate Variable Expressions | Pre-Algebra Printable - Free Printable

Let’s go through each problem one by one. We’re asked to evaluate each expression for the given values of the variables. That means we plug in the numbers and simplify.

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Problem 1:
Expression: \( x + \frac{1}{2} \)
Given: \( x = \frac{1}{2} \)

Plug in:
\( \frac{1}{2} + \frac{1}{2} = 1 \)

✔ Answer: 1

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Problem 2:
Expression: \( x + y + z \)
Given: \( x = 2, y = 3, z = 4 \)

Plug in:
\( 2 + 3 + 4 = 9 \)

✔ Answer: 9

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Problem 3:
Expression: \( \frac{x + y}{z} \)
Given: \( x = 2, y = 3, z = 4 \)

Plug in:
\( \frac{2 + 3}{4} = \frac{5}{4} \)

✔ Answer: \(\frac{5}{4}\)

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Problem 4:
Expression: \( 3x - 2y \)
Given: \( x = 3, y = -4 \)

Plug in:
\( 3(3) - 2(-4) = 9 + 8 = 17 \)

✔ Answer: 17

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Problem 5:
Expression: \( 3(2x - 3y) \)
Given: \( x = 4, y = -1 \)

First, inside parentheses:
\( 2(4) - 3(-1) = 8 + 3 = 11 \)
Then multiply by 3:
\( 3 \times 11 = 33 \)

✔ Answer: 33

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Problem 6:
Expression: \( \frac{5x - 2y}{2} \)
Given: \( x = 3, y = -4 \)

Numerator:
\( 5(3) - 2(-4) = 15 + 8 = 23 \)
Divide by 2:
\( \frac{23}{2} \)

✔ Answer: \(\frac{23}{2}\)

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Problem 7:
Expression: \( \frac{abc}{2} \)
Given: \( a = 3, b = -4, c = 5 \)

Multiply:
\( 3 \times (-4) \times 5 = -60 \)
Divide by 2:
\( \frac{-60}{2} = -30 \)

✔ Answer: -30

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Problem 8:
Expression: \( \frac{2x^2 + y^2}{z} \)
Given: \( x = -2, y = -3, z = 5 \)

First, square the numbers:
\( x^2 = (-2)^2 = 4 \) → \( 2x^2 = 2 \times 4 = 8 \)
\( y^2 = (-3)^2 = 9 \)
Add: \( 8 + 9 = 17 \)
Divide by z: \( \frac{17}{5} \)

✔ Answer: \(\frac{17}{5}\)

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Problem 9:
Expression: \( \frac{2x + 3y}{4} \)
Given: \( x = -3, y = -4, z = 14 \) ← note: z is not used here

Plug in x and y:
\( 2(-3) + 3(-4) = -6 -12 = -18 \)
Divide by 4: \( \frac{-18}{4} = -\frac{9}{2} \)

✔ Answer: \(-\frac{9}{2}\)

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Problem 10:
Expression: \( \frac{x(x + 3y)}{4} \)
Given: \( x = 3, y = -4 \)

First, compute inside parentheses:
\( x + 3y = 3 + 3(-4) = 3 - 12 = -9 \)
Now multiply by x:
\( 3 \times (-9) = -27 \)
Divide by 4: \( \frac{-27}{4} \)

✔ Answer: \(-\frac{27}{4}\)

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Final Answer:
1. 1
2. 9
3. \(\frac{5}{4}\)
4. 17
5. 33
6. \(\frac{23}{2}\)
7. -30
8. \(\frac{17}{5}\)
9. \(-\frac{9}{2}\)
10. \(-\frac{27}{4}\)