Please help me and
explain how you got the answer

Answer:
x = 7°
Step-by-step explanation:
∠WST is an exterior angle of the triangle
The two interior angles (5x - 1) and (57) add up to WST ( 12x + 7) because they are the non-adjacent interior angles
Solve:
(5x - 1) + (57) = (12x + 7)
5x - 1 = 12x - 50
-1 = 7x - 50
49 = 7x
x = 7
-Chetan K