Respuesta :

Space

Answer:

m∠B = 69°

General Formulas and Concepts:

  • Order of Operations: BPEMDAS
  • Equality Properties
  • Complementary Angles add up to 90°

Step-by-step explanation:

Step 1: Define

m∠A = (x + 9)°

m∠B = (7x - 15)°

Step 2: Set up equation

m∠A + m∠B = 90°

(x + 9)° + (7x - 15)° = 90°

Step 3: Solve for x

  1. Combine like terms:                    8x - 6 = 90
  2. Add 6 to both sides:                    8x = 96
  3. Divide both sides by 8:                x = 12

Step 4: Find m∠B

  1. Define:                    m∠B = (7x - 15)°
  2. Substitute:              m∠B = (7(12) - 15)°
  3. Multiply:                  m∠B = (84 - 15)°
  4. Subtract:                 m∠B = 69°

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