Answer:
∠ B = 15°
Step-by-step explanation:
Complementary angles sum to 90° , that is
∠ A + ∠ B = 90 , substitute values
8x + 27 + 6x - 21 = 90
14x + 6 = 90 ( subtract 6 from both sides )
14x = 84 ( divide both sides by 14 )
x = 6
Thus
∠ B = 6x - 21 = 6(6) - 21 = 36 - 21 = 15°