Answer:
x = -8
m∠BDC = 68°
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
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
- Combine like terms: -15x + 60 = 180
- Isolate x term: -15x = 120
- Isolate x: x = -8
Step 3: Find m∠BDC
- Define: m∠BDC = (-7x + 12)°
- Substitute in x: m∠BDC = (-7(-8) + 12)°
- Multiply: m∠BDC = (56 + 12)°
- Add: m∠BDC = 68°