Practice worksheet for solving multi-step equations with problems and error correction exercises.

Let's solve each of these multi-step equations step by step, showing all work. We'll also identify and correct the mistakes in problems 7 and 8.

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1. $ 4(3x + 7) = 64 + 4x $

Step 1: Distribute the 4 on the left side:
$$
4 \cdot 3x + 4 \cdot 7 = 64 + 4x \\
12x + 28 = 64 + 4x
$$

Step 2: Subtract $4x$ from both sides:
$$
12x - 4x + 28 = 64 \\
8x + 28 = 64
$$

Step 3: Subtract 28 from both sides:
$$
8x = 64 - 28 \\
8x = 36
$$

Step 4: Divide by 8:
$$
x = \frac{36}{8} = \frac{9}{2} = 4.5
$$

✔ Answer: $ x = \frac{9}{2} $ or $ 4.5 $

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2. $ 16 = -4(2x - 5) $

Step 1: Distribute the $-4$:
$$
16 = -4 \cdot 2x + (-4) \cdot (-5) \\
16 = -8x + 20
$$

Step 2: Subtract 20 from both sides:
$$
16 - 20 = -8x \\
-4 = -8x
$$

Step 3: Divide by $-8$:
$$
x = \frac{-4}{-8} = \frac{1}{2}
$$

✔ Answer: $ x = \frac{1}{2} $

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3. $ -8(6 + 5x) = 3x - 5 $

Step 1: Distribute $-8$:
$$
-8 \cdot 6 + (-8) \cdot 5x = 3x - 5 \\
-48 - 40x = 3x - 5
$$

Step 2: Add $40x$ to both sides:
$$
-48 = 3x + 40x - 5 \\
-48 = 43x - 5
$$

Step 3: Add 5 to both sides:
$$
-48 + 5 = 43x \\
-43 = 43x
$$

Step 4: Divide by 43:
$$
x = \frac{-43}{43} = -1
$$

✔ Answer: $ x = -1 $

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4. $ 33 = -3(1 + 4x) $

Step 1: Distribute $-3$:
$$
33 = -3 \cdot 1 + (-3) \cdot 4x \\
33 = -3 - 12x
$$

Step 2: Add 3 to both sides:
$$
33 + 3 = -12x \\
36 = -12x
$$

Step 3: Divide by $-12$:
$$
x = \frac{36}{-12} = -3
$$

✔ Answer: $ x = -3 $

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5. $ \frac{4x - 2}{5} = 0.4 $

Step 1: Multiply both sides by 5 to eliminate the denominator:
$$
4x - 2 = 0.4 \cdot 5 \\
4x - 2 = 2
$$

Step 2: Add 2 to both sides:
$$
4x = 2 + 2 = 4
$$

Step 3: Divide by 4:
$$
x = \frac{4}{4} = 1
$$

✔ Answer: $ x = 1 $

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6. $ \frac{2}{3}x - 6 = \frac{1}{3}x + 3 $

Step 1: Subtract $ \frac{1}{3}x $ from both sides:
$$
\frac{2}{3}x - \frac{1}{3}x - 6 = 3 \\
\frac{1}{3}x - 6 = 3
$$

Step 2: Add 6 to both sides:
$$
\frac{1}{3}x = 3 + 6 = 9
$$

Step 3: Multiply both sides by 3:
$$
x = 9 \cdot 3 = 27
$$

✔ Answer: $ x = 27 $

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7. Find the mistake and correct it:

Given:
$$
\frac{1}{4}(12x - 16) = 2x
$$

Incorrect Step (assumed):
Suppose someone wrote:
$$
\frac{1}{4} \cdot 12x - 16 = 2x \quad \text{(This is wrong!)}
$$

Mistake: The distributive property was not applied correctly. The $ \frac{1}{4} $ must multiply both terms inside the parentheses.

Correct Work:
$$
\frac{1}{4}(12x - 16) = 2x \\
\Rightarrow \frac{1}{4} \cdot 12x - \frac{1}{4} \cdot 16 = 2x \\
\Rightarrow 3x - 4 = 2x
$$

Now solve:
$$
3x - 4 = 2x \\
3x - 2x = 4 \\
x = 4
$$

✔ Corrected Answer: $ x = 4 $

> ✘ Mistake: Not distributing $ \frac{1}{4} $ to both terms.
> ✔ Correction: $ \frac{1}{4}(12x - 16) = 3x - 4 $

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8. Find the mistake and correct it:

Given:
$$
-4 + 14x = -12 + 12x
$$

Suppose someone did this:

Incorrect Step (assumed):
Maybe they subtracted $12x$ from both sides but made a sign error:
$$
-4 + 14x - 12x = -12 \\
-4 + 2x = -12 \\
2x = -12 + 4 = -8 \\
x = -4
$$

Wait — that’s actually correct, so let’s check if there’s another common mistake.

But perhaps the mistake is in not isolating variables properly.

Let’s assume the common mistake is:

✘ Incorrect reasoning: "Add 12 to both sides, then subtract $14x$" → leads to errors.

But let’s do it correctly:

Correct Solution:

$$
-4 + 14x = -12 + 12x
$$

Step 1: Subtract $12x$ from both sides:
$$
-4 + 14x - 12x = -12 \\
-4 + 2x = -12
$$

Step 2: Add 4 to both sides:
$$
2x = -12 + 4 = -8
$$

Step 3: Divide by 2:
$$
x = -4
$$

✔ So the solution is correct: $ x = -4 $

But what could be the mistake?

Common Mistake Example:
Someone might write:
$$
-4 + 14x = -12 + 12x \\
\Rightarrow 14x - 12x = -12 + 4 \quad \text{(wrong sign)} \\
\Rightarrow 2x = -8 \quad \text{→ still correct?}
$$

Wait — actually, that’s correct.

Another possible mistake: adding 12x instead of subtracting.

Suppose someone does:
$$
-4 + 14x = -12 + 12x \\
\Rightarrow -4 + 14x + 12x = -12 \\
\Rightarrow -4 + 26x = -12 \quad \text{(Wrong!)}
$$

Then:
$$
26x = -8 \Rightarrow x = -\frac{4}{13}
$$

✘ This is incorrect because you should subtract $12x$, not add.

So the mistake is likely:
> Adding $12x$ instead of subtracting it.

Correct Way:
$$
-4 + 14x = -12 + 12x \\
\text{Subtract } 12x \text{ from both sides:} \\
-4 + 2x = -12 \\
\text{Add 4: } 2x = -8 \\
x = -4
$$

✔ Final Answer: $ x = -4 $

> ✘ Mistake: Adding $12x$ instead of subtracting it (or incorrectly combining like terms).
> ✔ Correct: Subtract $12x$ from both sides.

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✔ Final Answers Summary:

| Problem | Answer |
|--------|--------|
| 1 | $ x = \frac{9}{2} $ |
| 2 | $ x = \frac{1}{2} $ |
| 3 | $ x = -1 $ |
| 4 | $ x = -3 $ |
| 5 | $ x = 1 $ |
| 6 | $ x = 27 $ |
| 7 | Mistake: Did not distribute $ \frac{1}{4} $ to both terms. Correction: $ 3x - 4 = 2x $, so $ x = 4 $. |
| 8 | Mistake: Likely added $12x$ instead of subtracting it. Correction: Subtract $12x$, get $ x = -4 $. |

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