Question

Solve by using substitution -5x-y=12 y=-4x-9

Answer 1

(-3, 3)

General Formulas and Concepts:

Pre-Algebra

• Order of Operations: BPEMDAS
• Equality Properties

Algebra I

• Solving systems of equations using substitution/elimination

Explanation:

Step 1: Define systems

-5x - y = 12

y = -4x - 9

Step 2: Solve for x

Substitution

1. Substitute in y: -5x - (-4x - 9) = 12
2. Distribute negative: -5x + 4x + 9 = 12
3. Combine like terms: -x + 9 = 12
4. Subtract 9 on both sides: -x = 3
5. Divide -1 on both sides: x = -3

Step 3: Solve for y

1. Define original equation: y = -4x - 9
2. Substitute in x: y = -4(-3) - 9
3. Multiply: y = 12 - 9
4. Subtract: y = 3