Question

Solve with substitution
y = x - 15
y = 4x

Answer 1

(-5, -20)

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

1. Brackets
2. Parenthesis
3. Exponents
4. Multiplication
5. Division
6. Addition
7. Subtraction

• Left to Right

Equality Properties

• Multiplication Property of Equality
• Division Property of Equality
• Addition Property of Equality
• Subtraction Property of Equality

Algebra I

• Coordinates (x, y)
• Solving systems of equations using substitution/elimination

Explanation:

Step 1: Define

y = x - 15

y = 4x

Step 2: Solve for x

Substitution

1. Substitute in y: 4x = x - 15
2. [Subtraction Property of Equality] Subtract x on both sides: 3x = -15
3. [Division Property of Equality] Divide 3 on both sides: x = -5

Step 3: Solve for y

1. Define original equation: y = 4x
2. Substitute in x: y = 4(-5)
3. Multiply: y = -20