Math Problem Statement

Solve by substitution

-x + 4y = -12, 3x - 6y = 6. Solve by substitution.

Solution

We are given the system of linear equations:

- x + 4y &= -12 \quad \text{(1)} \\ 3x - 6y &= 6 \quad \text{(2)} \end{aligned}$$ Let's solve this system by substitution. ### Step 1: Solve for $$x$$ in terms of $$y$$ from equation (1). From equation (1): $$- x + 4y = -12$$ Solve for $$x$$: $$x = 4y + 12$$ ### Step 2: Substitute $$x = 4y + 12$$ into equation (2). Now, replace $$x$$ in equation (2) with $$4y + 12$$: $$3(4y + 12) - 6y = 6$$ Expand the equation: $$12y + 36 - 6y = 6$$ Simplify: $$6y + 36 = 6$$ Subtract 36 from both sides: $$6y = -30$$ Solve for $$y$$: $$y = -5$$ ### Step 3: Substitute

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Substitution Method

Formulas

Substitution method: Solve one equation for a variable and substitute into the other equation
Simplifying algebraic expressions

Theorems

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Suitable Grade Level

Grades 8-10