Question

Solve using substitution 6x + 7y = - 1 x-y = 15

Answer 1

Answer:

(8, -7)

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  

Distributive Property

Equality Properties

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

Algebra I

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

Step-by-step explanation:

Step 1: Define Systems

6x + 7y = -1

x - y = 15

Step 2: Rewrite Systems

x - y = 15

1. [Addition Property of Equality] Isolate x:                                                         x = y + 15

Step 3: Solve for y

Substitution

1. Substitute in x [1st Equation]:                                                                           6(y + 15) + 7y = -1
2. [Distributive Property] Distribute 6:                                                                 6y + 90 + 7y = -1
3. Combine like terms:                                                                                         13y + 90 = -1
4. [Subtraction Property of Equality] Isolate y term:                                           13y = -91
5. [Division Property of Equality] Isolate y:                                                         y = -7

Step 4: Solve for x

1. Substitute in y [2nd Equation]:                                                                         x - (-7) = 15
2. Simplify:                                                                                                             x + 7 = 15
3. [Subtraction Property of Equality] Isolate x:                                                   x = 8