Answer:
x = 6, ∠ B = 126°
Step-by-step explanation:
∠ A and ∠ B are alternate angles and congruent, so
8x + 78 = 2x + 114 ( subtract 2x from both sides )
6x + 78 = 114 ( subtract 78 from both sides )
6x = 36 ( divide both sides by 6 )
x = 6
Then
∠ B = 2x + 114 = 2(6) + 114 = 12 + 114 = 126°
