Respuesta :

Space

Answer:

x = -8

m∠BDC = 68°

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

Geometry

  • Definition of a Line: A line is 180°

Step-by-step explanation:

Step 1: Set up Equation

m∠BDC + m∠CDA = 180°

(-7x + 12)° + (-8x + 48)° = 180°

Step 2: Solve for x

  1. Combine like terms:                    -15x + 60 = 180
  2. Isolate x term:                              -15x = 120
  3. Isolate x:                                       x = -8

Step 3: Find m∠BDC

  1. Define:                    m∠BDC = (-7x + 12)°
  2. Substitute in x:       m∠BDC = (-7(-8) + 12)°
  3. Multiply:                  m∠BDC = (56 + 12)°
  4. Add:                        m∠BDC = 68°