Precalculus Examples

$21 x - 5 = 5 (4 x + 5) - 20$

Step 1

Simplify $5 (4 x + 5) - 20$ .

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Step 1.1

Simplify each term.

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Step 1.1.1

Apply the distributive property.

$21 x - 5 = 5 (4 x) + 5 \cdot 5 - 20$

Step 1.1.2

Multiply $4$ by $5$ .

$21 x - 5 = 20 x + 5 \cdot 5 - 20$

Step 1.1.3

Multiply $5$ by $5$ .

$21 x - 5 = 20 x + 25 - 20$

Step 1.2

Subtract $20$ from $25$ .

$21 x - 5 = 20 x + 5$

Step 2

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

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Step 2.1

Subtract $20 x$ from both sides of the equation.

$21 x - 5 - 20 x = 5$

Step 2.2

Subtract $20 x$ from $21 x$ .

$x - 5 = 5$

Step 3

Move all terms not containing $x$ to the right side of the equation.

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Step 3.1

Add $5$ to both sides of the equation.

$x = 5 + 5$

Step 3.2

Add $5$ and $5$ .

$x = 10$