Respuesta :

Space

Answer:

B.) 3

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

Algebra I

  • Solving systems of equations using substitution/elimination

Step-by-step explanation:

Step 1: Define Systems

x - y = -1

3x + 5y = 21

Step 2: Rewrite Systems

x - y = -1

  1. Add y to both sides:                    x = y - 1

Step 3: Redefine Systems

x = y - 1

3x + 5y = 21

Step 4: Solve for y

Substitution

  1. Substitute in x:                              3(y - 1) + 5y = 21
  2. Distribute 3:                                   3y - 3 + 5y = 21
  3. Combine like terms:                     8y - 3 = 21
  4. Add 3 to both sides:                     8y = 24
  5. Divide 8 on both sides:                y = 3

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