Algebra Examples

$y = 3 x - 4$ $- 3 y = - 9 x + 12$

Step 1

Replace all occurrences of $y$ with $3 x - 4$ in each equation.

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Step 1.1

Replace all occurrences of $y$ in $- 3 y = - 9 x + 12$ with $3 x - 4$ .

$- 3 (3 x - 4) = - 9 x + 12$

$y = 3 x - 4$

Step 1.2

Simplify the left side.

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Step 1.2.1

Simplify $- 3 (3 x - 4)$ .

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Step 1.2.1.1

Apply the distributive property.

$- 3 (3 x) - 3 \cdot - 4 = - 9 x + 12$

$y = 3 x - 4$

Step 1.2.1.2

Multiply.

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Step 1.2.1.2.1

Multiply $3$ by $- 3$ .

$- 9 x - 3 \cdot - 4 = - 9 x + 12$

$y = 3 x - 4$

Step 1.2.1.2.2

Multiply $- 3$ by $- 4$ .

$- 9 x + 12 = - 9 x + 12$

$y = 3 x - 4$

$- 9 x + 12 = - 9 x + 12$

$y = 3 x - 4$

$- 9 x + 12 = - 9 x + 12$

$y = 3 x - 4$

$- 9 x + 12 = - 9 x + 12$

$y = 3 x - 4$

$- 9 x + 12 = - 9 x + 12$

$y = 3 x - 4$

Step 2

Remove any equations from the system that are always true.

$y = 3 x - 4$

Step 3