please help i need the explanation to go look back at for similar questions in the future. last word is Bold.

Answer:
50
Step-by-step explanation:
The given angles in the triangle are vertically opposite angles. Hence;
9x - 4 = 8 + 7x
Collect the like terms
9x - 7x = 8 + 4
2x = 12
x = 12/2
x = 6
Get the bolded angle
Bolded angle= 8 + 7x
Blded angle = 8 + 7(6)
Bolded angle = 8 + 42
Bolded angle = 50