Basic Math Examples

$4 a = 12 - 3 (a - 3)$

Step 1

Simplify $12 - 3 (a - 3)$ .

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Step 1.1

Simplify each term.

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Step 1.1.1

Apply the distributive property.

$4 a = 12 - 3 a - 3 \cdot - 3$

Step 1.1.2

Multiply $- 3$ by $- 3$ .

$4 a = 12 - 3 a + 9$

Step 1.2

Add $12$ and $9$ .

$4 a = - 3 a + 21$

Step 2

Move all terms containing $a$ to the left side of the equation.

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Step 2.1

Add $3 a$ to both sides of the equation.

$4 a + 3 a = 21$

Step 2.2

Add $4 a$ and $3 a$ .

$7 a = 21$

Step 3

Divide each term in $7 a = 21$ by $7$ and simplify.

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Step 3.1

Divide each term in $7 a = 21$ by $7$ .

$\frac{7 a}{7} = \frac{21}{7}$

Step 3.2

Simplify the left side.

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Step 3.2.1

Cancel the common factor of $7$ .

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Step 3.2.1.1

Cancel the common factor.

$\frac{7 a}{7} = \frac{21}{7}$

Step 3.2.1.2

Divide $a$ by $1$ .

$a = \frac{21}{7}$

Step 3.3

Simplify the right side.

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Step 3.3.1

Divide $21$ by $7$ .

$a = 3$